Long-term antihypertensive effects of aliskiren, a direct renin inhibitor, in chronic hemodialysis patients

The renin-angiotensin-aldosterone system is not necessarily suppressed in end-stage renal disease patients undergoing dialysis. Of all the inhibitors of this system, the clinical efficacy of the renin inhibitor, aliskiren, has not been well demonstrated in dialysis patients. We evaluated the antihypertensive effect of aliskiren, administered as a single daily dose of 150 mg for 24 weeks, in 23 chronic hemodialysis patients (age 65 ± 12 years, 15 men and eight women) with blood pressure ≥140/90 mm Hg, and assessed the factors relating to blood pressure reduction. At 4 weeks, the average systolic blood pressure before the dialysis session was insignificantly reduced from 163 ± 10 mm Hg to 160 ± 15 mm Hg, while it was significantly lowered at 12 (154 ± 13 mm Hg) and 24 weeks (155 ± 10 mm Hg), although the pulse rate was not significantly altered. Serum K increased at 24 weeks from 4.9 ± 0.6 mEq/L to 5.2 ± 0.8 mEq/L. Only 10 out of 23 patients showed systolic blood pressure reduction by ≥10 mm Hg. Naturally, plasma renin immunoreactivity increased, while plasma renin activity, along with angiotensin II and aldosterone levels decreased. Basal levels of the components of the renin-angiotensin-aldosterone system were not significantly different in patients showing systolic blood pressure reduction by ≥10 mm Hg (n = 10) vs. those with <10 mm Hg changes (n = 13). The reduction in systolic blood pressure in all 23 patients taken as a whole correlated with changes in plasma renin activity (r = -0.432, P < 0.05) and angiotensin II (r = 0.467, P < 0.05). In chronic hemodialysis patients, aliskiren modestly lowers blood pressure over the long term, although the antihypertensive effect seems dependent on the changes, but not on the basal levels of plasma renin activity and angiotensin II.

Japanese traditional miso soup attenuates salt-induced hypertension and its organ damage in Dahl salt-sensitive rats

OBJECTIVE

We investigated the effects of long-term miso soup drinking on salt-induced hypertension in Dahl salt-sensitive (Dahl S) rats.

METHODS

Dahl S rats were divided into four groups that consumed 1) water, 2) a 0.9% NaCl solution, 3) a 1.3% sodium NaCl solution, or 4) miso soup containing 1.3% NaCl. They were followed for 8 wk. Systolic blood pressure and hypertensive organ damage were determined.

RESULTS

Systolic blood pressure increased in an age- and dose-dependent manner in Dahl S rats drinking salt solutions. The systolic blood pressure increase was significantly less in the Dahl S rats that drank miso soup, although the ultimate cumulative salt loading was greater than that in the Dahl S rats given the 1.3% NaCl solution. This blood pressure decrease was associated with a morphologic attenuation of glomerular sclerosis in the kidney and collagen infiltration in the heart. Urinary protein excretions were less in the miso group than in the rats given the 1.3% NaCl solution. The fractional excretion of sodium was increased and that of potassium was decreased in Dahl S rats given the 1.3% NaCl solution, and these effects were reversed in rats given miso soup toward the values of the control.

CONCLUSION

We found that long-term miso soup drinking attenuates the blood pressure increase in salt-induced hypertension with organ damage. This may be caused by a possible retardation of sodium absorption in the gastrointestinal tract or by the direct effects of nutrients in the miso soup from soybeans. The decrease was associated with decreases in cardiovascular and renal damage.

Sodium alginate oligosaccharides attenuate hypertension and associated kidney damage in Dahl salt-sensitive rats fed a high-salt diet

OBJECTIVES

In this article, the antihypertensive effects of sodium alginate oligosaccharides, enzymatic products of high molecular natural alginate from sea weeds, in Dahl salt-sensitive (Dahl S) rats were investigated.

MATERIAL AND METHODS

Dahl S rats fed a high-salt (4% NaCl) diet were treated with sodium alginate oligosaccharides (4% or 8% w/w) for 7 weeks. Systolic blood pressure (SBP) was measured by the tail-cuff method, and hypertensive cardiovascular benefits and kidney damage were assessed. Glomerular function and morphological sclerosis were determined.

RESULTS

SBP increased in an age-dependent manner in the untreated Dahl S rats. Sodium alginate oligosaccharide treatment attenuated the increase in SBP in a dose-dependent manner. The heart and aortic walls weighed less in the rats treated with sodium alginate oligosaccharides than in the untreated rats. The SBP reduction was associated with a decrease in urinary protein excretion and an increase in the creatinine clearance rate. Sodium alginate oligosaccharides significantly attenuated hypertensive glomerular sclerosis and arterial injury in the kidney. Fractional excretion of sodium (FENa) decreased in low-salt Dahl S rats and increased with a salt challenge. The alginate oligosaccharides decreased FENa in high-salt Dahl S rats.

CONCLUSIONS

The results of this study suggest that sodium alginate oligosaccharides attenuate salt-induced hypertension in Dahl S rats. This reduction is associated with decreases in cardiovascular and renal damage.

Combination of angiotensin II receptor antagonist with calcium channel blocker or diuretic as antihypertensive therapy for patients with chronic kidney disease

We compared treatment with an angiotensin II receptor antagonist (ARB) and a calcium channel blocker (CCB) combination and a fixed-dose ARB and thiazide diuretic in 18 chronic kidney disease (CKD) patients. A randomized crossover study was performed using a fixed-dose combination of losartan-hydrochlorothiazide or losartan combined with controlled-release nifedipine. Both systolic blood pressure (SBP) and diastolic blood pressures (DBPs) were lower during the nifedipine period than during the diuretic period. No significant difference was observed in urinary albumin excretion, but the estimated glomerular filtration rate was higher in the nifedipine than in the diuretic period. Serum uric acid and low-density lipoprotein cholesterol were higher in the diuretic than in the nifedipine period. A significantly low cardio-ankle vascular index, an index of arterial wall stiffness, was observed in the nifedipine period. A combination of ARB and a controlled-release nifedipine at 20-40 mg used showed a superior antihypertensive effect in CKD patients compared to a fixed-dose combination of losartan 50 mg-hydrochlorothiazide 12.5 mg in terms of blood control. The former combination is considered advantageous for maintaining renal function and artery wall elasticity without influencing uric acid or lipid metabolism.

Efonidipine reduces proteinuria and plasma aldosterone in patients with chronic glomerulonephritis

Efonidipine, a dihydropirydine calcium channel blocker, has been shown to dilate the efferent glomerular arterioles as effectively as the afferent arterioles. The present study compared the chronic effects of efonidipine and amlodipine on proteinuria in patients with chronic glomerulonephritis. The study subjects were 21 chronic glomerulonephritis patients presenting with spot proteinuria greater than 30 mg/dL and serum creatinine concentrations of <or=1.3 mg/dL in men or <or=1.1 mg/dL in women. All patients were receiving antihypertensive medication or had a blood pressure >or=130/85 mmHg. Efonidipine 20-60 mg twice daily and amlodipine 2.5-7.5 mg once daily were given for 4 months each in a random crossover manner. In both periods, calcium channel blockers were titrated when the BP exceeded 130/85 mmHg. Blood sampling and urinalysis were performed at the end of each treatment period. The average blood pressure was comparable between the efonidipine and the amlodipine periods (133+/-10/86+/-5 vs. 132+/-8/86+/-5 mmHg). Urinary protein excretion was significantly less in the efonidipine period than in the amlodipine period (1.7+/-1.5 vs. 2.0+/-1.6 g/g creatinine, p=0.04). Serum albumin was significantly higher in the efonidipine period than the amlodipine period (4.0+/-0.5 vs. 3.8+/-0.5 mEq/L, p=0.03). Glomerular filtration rate was not significantly different between the two periods. Plasma aldosterone was lower in the efonidipine period than in the amlodipine period (52+/-46 vs. 72+/-48 pg/mL, p=0.009). It may be concluded that efonidipine results in a greater reduction of plasma aldosterone and proteinuria than amlodipine, and that these effects occur by a mechanism independent of blood pressure reduction. A further large-scale clinical trial will be needed in order to apply the findings of this study to the treatment of patients with renal disease.

Benazepril slows progression of renal dysfunction in patients with non-diabetic renal disease

AIM

The present study examined the effects of benazepril, an angiotensin-converting enzyme inhibitor, on the progression of renal insufficiency in patients with non-diabetic renal disease.

METHODS

Fifteen patients with non-diabetic renal disease whose serum creatinine (Cr) ranged from 1.5 to 3.0 mg/dL were given either benazepril (2.5-5 mg) or placebo once daily for 1 year in a random crossover manner. In both periods, antihypertensive medications were increased if blood pressure was greater than 130/85 mmHg. Blood sampling and urinalysis were performed bimonthly throughout the study period.

RESULTS

Blood pressure was similar when comparing the benazepril and the placebo periods (128+/-12/83+/-6 vs 129+/-10/83+/-7 mmHg). Serum Cr significantly increased from 1.62+/-0.18 to 1.72+/-0.30 mg/dL (P=0.036) during the placebo period, while there was no statistically significant increase in serum Cr during the benazepril period (from 1.67+/-0.17 to 1.71+/-0.27 mg/dL). The slope of decrease of the reciprocal of serum Cr was steeper in the placebo period than in the benazepril period (-0.073+/-0.067 vs-0.025+/-0.096/year, P=0.014). Urinary protein excretion was lower during the benazepril period than during the placebo period (0.57+/-0.60 vs 1.00+/-0.85 g/gCr, P=0.006). Serum K was significantly higher in the benazepril period than in the placebo period (4.4+/-0.5 vs 4.2+/-0.5 mEq/L, P<0.001), but no patient discontinued benazepril therapy as a result of hyperkalemia.

CONCLUSION

Long-term benazepril treatment decreased the progression of renal dysfunction in patients with non-diabetic renal disease by a mechanism that is independent of blood pressure reduction.

Urinary liver-type fatty acid binding protein as a useful biomarker in chronic kidney disease

BACKGROUND

We reported that urinary L-FABP reflected the progression of chronic kidney disease (CKD). This study is aimed to evaluate the clinical significance of urinary liver type fatty acid binding protein (L-FABP) as a biomarker for monitoring CKD.

METHODS

Urinary L-FABP was measured using human L-FABP ELISA kit (CMIC.Co., Ltd., Tokyo, Japan). The relations between urinary L-FABP and clinical parameters were evaluated in non-diabetic CKD (n = 48) for a year. In order to evaluate the influence of serum L-FABP derived from liver upon urinary L-FABP, both serum and urinary L-FABP were simultaneously measured in patients with CKD (n = 73).

RESULTS

For monitoring CKD, the cut-off value in urinary L-FABP was determined as 17.4 microg/g.cr. by using a receiver operating characteristics (ROC) curve. Renal function deteriorated significantly more in patients with 'high' urinary L-FABP (n = 36) than in those with 'low' L-FABP (n = 12). The decrease in creatinine clearance was accompanied by an increase in urinary L-FABP, but not in urinary protein. Serum L-FABP in patients with CKD was not correlated with urinary L-FABP.

CONCLUSION

Urinary excretion of L-FABP increases with the deterioration of renal function. Serum L-FABP did not influence on urinary L-FABP. Urinary L-FABP may be a useful clinical biomarker for monitoring CKD.

Estimation of pesticide runoff from paddy fields to rural rivers

The runoff characteristics of pesticides from paddy fields to rural rivers were investigated over a period of three years in Hokkaido Prefecture, Japan. High pesticide concentrations were usually observed in rivers during pesticide application periods. In one year, the growth of rice seedlings slowed down after transplantation owing to low temperatures and lack of sunshine, and many farmers delayed herbicide application. In that year, high-concentration runoff of herbicides in rivers was observed 1-3 weeks later than in average years. The pesticide runoff rates ranged from 0.3% for fenthion to 42% for benfuresate. The runoff rates of pesticides applied post-flood were large. Furthermore, the larger the water solubility of the pesticide, the larger the runoff rate. The highest concentrations of herbicides in paddy water were observed on the day of application or 1-2 days later, and the concentrations decreased exponentially afterwards. The half-lives of the herbicides ranged from 1.2 days for pretilachlor and esprocarb to 5 days for simetryn; the concentrations of the herbicides in paddy water had decreased to 1/10 of their initial concentrations by about 7 days after application. Therefore, the runoff amounts of pesticides from paddy fields could be decreased by improving irrigation-water management.

Urinary excretions of lipocalin-type prostaglandin D2 synthase predict the development of proteinuria and renal injury in OLETF rats

BACKGROUND

Otsuka Long-Evans Tokushima Fatty (OLETF) rats genetically develop diabetes which is associated with hypertension. In preliminary studies, urinary excretions of L-PGDS (lipocaline-type prostaglandin D synthase) increase before diabetic nephropathy obviously develops, and this may predict progression of renal injury following diabetes. In the present study, we attempted to define whether urinary excretions of L-PGDS behave as the predictor of development of diabetic nephropathy in OLETF rats.

METHODS

We investigated alterations of urinary L-PGDS excretions during the establishment of diabetes and assessed the relationship between the L-PGDS excretions and renal function in OLETF rats. Furthermore, we treated OLETF rats with troglitazone and analysed the effects on L-PGDS metabolisms. Urinary L-PGDS was measured by immunoenzyme assay and the occurrence of L-PGDS and its mRNA in the kidney was assessed by immunohistochemistry and a PCR method.

RESULTS

Urinary excretions of L-PGDS were significantly higher in OLETF rats than non-diabetic Long-Evans Tokushima Otsuka (LETO) rats. The excretions age-dependently increased in OLETF and this increase appeared to be due to increased glomerular permeability to L-PGDS. Messenger RNA and antigenicity of L-PGDS were demonstrated in renal tissue; however, the de novo synthesis of L-PGDS mRNA seemingly contributed to urinary L-PGDS excretions much less than glomerular filtration. Multiple regression analysis revealed that urinary L-PGDS was determined by urinary protein excretions, and not by high blood pressure per se. Conversely, urinary proteinuria in the established diabetic nephropathy was predicted by urinary L-PGDS excretions in the early stage of diabetes.

CONCLUSIONS

Urinary excretions of L-PGDS are likely to reflect the underlying increase in glomerular permeability. This property may be useful to predict forthcoming glomerular damage following diabetes in OLETF rats.

Clinical evaluation of urinary excretion of liver-type fatty acid-binding protein as a marker for the monitoring of chronic kidney disease: a multicenter trial

To confirm the clinical usefulness of the measurement of urinary liver-type fatty acid-binding protein (L-FABP) in chronic kidney disease (CKD), we carried out a multicenter trial. Clinical markers were measured in patients with nondiabetic CKD (n = 48) every 1 to 2 months for a year. We divided patients retrospectively into progression (n = 32) and nonprogression (n = 16) groups on the basis of the rate of disease progression, then assessed several clinical markers. Initially creatinine clearance (Ccr) was similar in the 2 groups; however, the urinary L-FABP level was significantly higher in the former group than in the latter (111.5 vs 53 microg/g creatinine, P < .001). For the monitoring CKD, we set the cutoff values for urinary L-FABP and urinary protein at 17.4 microg/g creatinine and 1.0 g/g creatinine, respectively. Urinary L-FABP was more sensitive than urinary protein in predicting the progression of CKD (93.8% and 68.8%, respectively). However, urinary protein showed greater specificity than did urinary L-FABP (93.8% and 62.5%, respectively). Over time, the progression of CKD tended to correlate with changes in urinary L-FABP (r = - .32, P < .05), but not in urinary protein (r = .18, not significant). The dynamics of urinary protein differed from that of urinary L-FABP, which increased as Ccr declined. Urinary L-FABP is more sensitive than urinary protein in predicting the progression of CKD. Urinary excretion of L-FABP increases with the deterioration of kidney function. Urinary L-FABP is therefore a useful clinical marker in the monitoring of CKD.

Comparison of once-daily nifedipine controlled-release with twice-daily nifedipine retard in the treatment of essential hypertension

AIMS

Nifedipine is a short-acting calcium antagonist formulated into several different oral preparations, each of which may have different effects on haemodynamics and autonomic nervous function. We compared the effects of nifedipine controlled-release (CR) and nifedipine retard on 24-h blood pressure, heart rate, rate-pressure product, and power spectral measures of heart rate variability in patients with essential hypertension.

METHODS

After 4 weeks of a drug-free period, 25 patients were randomized to receive either once-daily treatment with nifedipine CR (20-40 mg daily; 12 patients) or twice-daily treatment with nifedipine retard (20-40 mg daily; 13 patients) for 12 weeks. The ambulatory blood pressure, heart rate, and ECG R-R intervals were measured during a 24-h period using a portable recorder (TM-2425) at the end of the drug-free and the treatment periods. A power-spectral analysis of R-R intervals was performed to obtain the low-frequency (LF) and high-frequency (HF) components.

RESULTS

Nifedipine CR and nifedipine retard reduced 24-h blood pressure significantly by 15.9 +/- 3.2 (SE)/8.7 +/- 1.4 mmHg and by 10.9 +/- 2.8/9.4 +/- 1.7 mmHg, respectively, after the 12-week treatment. Nifedipine CR did not change the 24-h heart rate significantly, while nifedipine retard increased it significantly by 3.9 +/- 2.1 beats min(-1). Nifedipine CR produced a significant reduction in rate-pressure product throughout a 24-h period, while nifedipine retard did not change the rate-pressure product significantly. In addition, nifedipine retard significantly decreased the 24-h and daytime average values of the LF and HF components, while nifedipine CR affected the nighttime LF component alone and did not change the HF component throughout a 24-h period.

CONCLUSIONS

These results demonstrate that both nifedipine CR and nifedipine retard are effective as antihypertensive agents, but nifedipine CR has less influence on the autonomic nervous system and heart rate than nifedipine retard.

Lipocalin-type prostaglandin D synthase in urine in adriamycin-induced nephropathy of mice

BACKGROUND/AIMS

Lipocalin-type prostaglandin D synthase (L-PGDS), an enzyme converting prostaglandin H(2) to prostaglandin D(2), occurs particularly in the cardiovascular system. Urinary L-PGDS excretion is increased in diabetes prior to overt proteinuria, suggesting that it is a predictor of renal injury. In this study, we tested the hypothesis that L-PGDS excretion reflects renal injury in primary glomerular diseases using Adriamycin-induced nephropathy in mice.

METHODS

Twenty 6-week-old ICR female mice were intravenously given a dose of 25 mg Adriamycin/kg body weight through the tail vein. 24-hour urine was collected every day, and blood samples were obtained.

RESULTS

The mice developed significant albuminuria from day 3 onward (p < 0.05), which was followed by overt proteinuria from day 4 (p < 0.05). Histological examination revealed focal mesangial expansion with partial tubular atrophy. Urinary L-PGDS excretion significantly increased from day 1 onward (p < 0.05), and apparently preceded the increase in urinary albumin excretions. Either serum L-PGDS or creatinine levels were not changed by administration of Adriamycin. However, serum creatinine levels were inversely correlated to urinary L-PGDS excretions (r = -0.88, p < 0.05). Immunohistochemistry showed that L-PGDS occurred in the tubules, but not in the glomeruli in Adriamycin mice and L-PGDS mRNA paralleled urinary L-PGDS excretion.

CONCLUSION

Urinary L-PGDS excretion is increased in Adriamycin-induced nephropathy, and this precedes overt albuminuria.

Inhibition of hydroxymethylglutaryl-coenzyme a reductase reduces Th1 development and promotes Th2 development

Several prospective clinical studies have indicated that hydroxymethylglutaryl-coenzyme A reductase inhibitors, statins, prevent cardiovascular events in part through their antiinflammatory properties. Because inflammation is positively and negatively regulated by T helper (Th) 1 cells and Th2 cells, respectively, we examined the effects of statins on the Th polarization in vitro and in vivo. Here we demonstrated that the statins tested, ie, cerivastatin, simvastatin, lovastatin, and atorvastatin, promoted Th2 polarization through both inhibition of Th1 development and augmentation of Th2 development of CD4+ T cells primed in vitro with anti-CD3 antibody and splenic antigen-presenting cells. Cerivastatin exerted most potent effect on modulation of Th1/Th2 development, and the effect was completely abrogated by an addition of mevalonate. Consistent with in vitro experiments, cerivastatin treatment decreased IFN-gamma production of lymph node cells from mice immunized with ovalbumin emulsified in complete Freund's adjuvant, indicating that Th1 development is also suppressed in an in vivo proinflammatory environment. In this murine model, cerivastatin significantly reduced mesangial matrix expansion of glomeruli in the kidney and attenuated proteinuria. The decrease of glomerular sclerosis by cerivastatin treatment was positively related to the suppression of interferon (IFN)-gamma-producing Th1 response in draining lymph node cells. Hence, these findings strongly suggest that statins' inhibition of 3-hydroxy-3-methylglutaryl-coenzyme A reductase regulates Th1/Th2 polarization in vivo and such a mechanism possibly plays a pathophysiological role in immune-related glomerular injury.

[A case of pseudo-Bartter's syndrome induced by long-term ingestion of furosemide delivered orally through health tea]

A 32-year-old woman with a three-year history of muscle weakness and hypokalemia, was admitted to our hospital because of hypokalemic periodic paralysis. Clinical and laboratory findings were consistent with Bartter's syndrome. Although she denied any ingestion of diuretics substantial quantities of furosemide were detected in her urine. She had been drinking health tea which contained about 90 mg of furosemide per teabag daily for five years. Four years after discontinuation of drinking the tea, the hypokalemia was completely ameliorated, but poor renal concentration ability is still present. We conclude that is a case of pseudo-Bartter's syndrome that was caused by long-term ingestion of the health tea supplemented illegally with furosemide, and suspect that such cases may be observed more frequently than currently thought.

Effects of the anti-platelet aggregation drug dilazep on cognitive function in Dahl salt-sensitive rats

Among the consequences of the increasing prolongation of lifespan is a worldwide increase in the number of cases of dementia or impaired cognition. In the present study, to test the hypothesis that mechanisms independent of high blood pressure are involved in maintaining cognitive function, we assessed the effects of long-term dilazep treatment on cognitive dysfunction in normotensive Dahl salt-sensitive (Dahl S) rats fed a low-salt diet, using the standard passive avoidance test. Normotensive Dahl S rats fed a 0.3% NaCl diet were treated for 6 months with low-dose dilazep (2.5 microg/ml in drinking water) or high-dose dilazep (12.5 microg/ml). Systolic blood pressure was within normotensive range throughout the study and did not differ among the experimental groups. The results of the passive avoidance test revealed that dilazep treatment attenuated the decline of latency time relative to that in the untreated control rats (control latency time, 235 s; low-dilazep group, 389 s; high-dilazep group, 397 s), suggesting that the cognitive function of normotensive Dahl S rats was improved by dilazep treatment. This improvement of cognition was associated with significant increases in the number of neuronal cells in the hippocampal region and with an increase in capillary length in dilazep-treated Dahl rats. In addition, the dilazep treatments significantly attenuated arteriolar injury of glomeruli in the kidney. These data suggest that dilazep treatment, through vascular and non-vascular effects, maintains the brain function in Dahl S rats susceptible to vascular injury and organ dysfunction.

Runoff characteristics of particulate pesticides in a river from paddy fields

Runoff characteristics of particulate pesticides from paddy fields have been intensively observed in the Koise River in Japan. The 8 pesticides that are applied to paddy fields were analyzed in both particulate and dissolved forms. The concentrations and the detection frequencies of particulate pesticides were lower than those of dissolved pesticides. The particulate pesticide concentrations in the river water were evaluated based on the soil sorption coefficient, particulate organic carbon concentration, and dissolved pesticide concentrations. The particulate pesticide concentrations in the river were higher than evaluated concentrations because the paddy soil contained more pesticides than did suspended solids in the river water discharged during rain events, and because the desorption rates of pesticides were slow. In observations made during rains, the particulate pesticide concentrations increased with the increases in both the discharge rate and the concentrations of suspended solids. The particulate loading was slight compared with dissolved loading, but particulate pesticides may be influenced by enclosed areas such as a lake or estuary because under such conditions particulate matter settles vertically and the pesticide decomposition rate in sediment is slow compared with that in water.

Left ventricular mass relates to average systolic blood pressure, but not loss of circadian blood pressure in stable hemodialysis patients: an ambulatory 48-hour blood pressure study

Although left ventricular hypertrophy (LVH) is a common complication which contributes substantially to high cardiovascular mortality and morbidity in end-stage renal failure, whether changes in blood pressure and alterations of circadian variation of blood pressure occur between the hemodialysis (HD) day and the interdialytic day, and if so, whether they influence the left ventricular mass (LVM) remain unknown. Thirty-five consecutive stable patients who had had a hematocrit value greater than 25% for the previous 6 months, who had been on the same antihypertensive drugs during this period, and who underwent HD 3 times a week were included. Echocardiograms were recorded after HD and then ambulatory blood pressure monitoring was recorded every hour for 48 h. The mean interdialytic body weight gain was less than 5% of dry weight. Patients with LVH had a higher average systolic blood pressure (SBP) at predialysis, postdialysis, on the HD day and on the interdialytic day than those without LVH despite the higher antihypertensive therapy rate. The majority of patients with LVH showed concentric hypertrophy and higher plasma natriuretic peptide levels. Irrespective of the presence of LVH, the average blood pressure value did not change between the HD day and the interdialytic day, and a loss of circadian blood pressure variation was observed on both the HD and interdialytic days. Univariate analysis revealed that LVM was significantly correlated with the average SBP at predialysis, postdialysis, on the HD day, on the interdialytic day and over 48 h (r= 0.48, r=0.61, r=0.67, r=0.67, r=0.73, respectively; all p<0.05). Multiple regression analysis revealed that 48-h SBP was independently associated with the LVM index. These results suggest that neither the loss of circadian blood pressure variation nor the changes of blood pressure between the HD and interdialytic days was of major etiologic importance in the development of LVH, and that the absolute value of the 48-hour average SBP may be an important risk factor for concentric LVH in stable HD patients.

Measurement of serum low density lipoprotein-cholesterol in patients with hypertriglycemia

Low density lipoprotein-cholesterol (LDL-c) concentration measured by a homogeneous enzymatic assay was reported to correlate well with the modified beta-quantification assay, especially in samples with high triglyceride (TG) concentration. In this study, we evaluated a homogeneous enzymatic assay, Cholestest-LDL assay system, in hypertriglycemic patient samples, and found that 56% (9/16) of serum samples with intermediate TG concentrations (2.27-4.52 mmol/L) showed more than 10% discrepancy with concentration by the modified beta-quantification assay. Such serum samples originated from patients with hyperglycemia of type II a (three cases), type II b (two cases), type III (one case), and type IV (six cases). Differential staining of cholesterol and triglyceride after agarose gel electrophoresis revealed that these serum samples contained significant amounts of intermediate fractions between pre-beta- and beta-lipoproteins. Since lipoprotein (a), which migrates between pre-beta- and beta-lipoproteins, is not correlated with the discrepancy, we believe the intermediate fraction consists of intermediate density lipoprotein (IDL) and a chylomicron remnant. A part of IDL and chylomicron remnant, which contain a significant amount of triglyceride, might be measured as LDL-c by the homogeneous enzymatic assay, but not by the modified beta-quantification assay.

Long-term inhibition of renin-angiotensin system sustains memory function in aged Dahl rats

The Dahl salt-sensitive (DS) rat, a genetic model of salt-induced hypertension in humans, is more likely to develop severe vascular injuries than a rat with spontaneous hypertension. We designed an experiment to scrutinize the effects of renin-angiotensin inhibition on cognitive dysfunction in the aged, normotensive DS with a passive avoidance test. Eighteen months of treatment with a very low dose of the angiotensin-converting enzyme (ACE) inhibitor cilazapril (2.5 microg/mL in drinking water) or the angiotensin II type 1 receptor antagonist E4177 did not reduce blood pressure throughout the experiment, although in the low dose cilazapril group (12.5 microg/mL in drinking water), blood pressure dropped within 6 months after treatment began. The cilazapril treatments dose-dependently improved memory function in the aged, normotensive DS fed a low-salt diet compared with the untreated, control rats. This improvement was associated with significant increases in hippocampal CA1 cells and capillary densities in the CA1 regions compared with those in the untreated DS. Similarly, E4177 slightly improved the memory dysfunction observed in the aged DS. The cells in the hippocampal CA1 region were restored slightly, but the capillary densities were not influenced by the receptor antagonist. On the other hand, the ACE inhibitor and receptor antagonist both attenuated urinary protein excretions with an improvement of glomerular sclerosis. These data suggest that long-term treatment with an ACE inhibitor improves memory dysfunction probably through restoration of capillary and hippocampal cells. The effects are due to the inhibition of the angiotensin II type 1 receptor and probably to the enhancement of the kallikrein-kinin system.

Amlodipine, a long-acting calcium channel blocker, attenuates morning blood pressure rise in hypertensive patients

1. The effects of once-daily calcium channel blockers with different plasma half-lives on diurnal blood pressure changes were examined in hypertensive patients. 2. Patients with essential hypertension, nine men and 13 women aged 61 +/- 2 years, were treated with amlodipine or nitrendipine in a random cross-over design for 12-16 weeks each. The study drugs were given once daily as monotherapy (n = 8) or in combination with other classes of antihypertensive drugs (n = 14). The plasma half-life of amlodipine is as long as 36 h, while that of nitrendipine is 10 h. At the end of each treatment period, 24 h ambulatory blood pressure and pulse rate were monitored. 3. Average office blood pressure was comparably controlled below 140/90 mmHg by either amlodipine or nitrendipine, both in the monotherapy and the combination therapy groups; however, pulse rate was greater in nitrendipine than in amlodipine either in the monotherapy (by 6 b.p.m., P < 0.05) or in the combination therapy (by 5 b.p.m., P < 0.01). 4. In 24 h blood pressure monitoring, morning (05.30-09.00 h) blood pressure was higher in nitrendipine than in amlodipine by 6/4 mmHg in the monotherapy (P < 0.05) and by 7/5 mmHg in the combination therapy (P < 0.03), although the blood pressure in the remainder of the 24 h did not differ between the two treatment periods. In addition, pulse rate in the daytime (09.30-18.00 h) was greater in nitrendipine than in amlodipine by 6 b.p.m. in the monotherapy (P < 0.01) and by 7 b.p.m. in the combination therapy (P < 0.02). 5. These results suggest slow pharmacokinetics of amlodipine provides an advantage in controlling morning blood pressure and mitigating reflex activation of the sympathetic nervous system.

High salt intake potentiates the renal vascular and glomerular damage caused by low doses of angiotensin II in uni-nephrectomized rats

OBJECTIVE

We recently reported that the renin-angiotensin system plays an important role in the progression of vascular and kidney injuries, even in Dahl salt-sensitive rats with volume-dependent hypertension. In this study, we investigated whether a high-salt diet increases susceptibility to kidney injury induced by angiotensin II in normotensive, uni-nephrectomized Sprague-Dawley rats, which mimics the condition of salt-volume repletion and blunted renin-angiotensin system.

METHODS

The rats were fed either a low-salt (0.3% NaCl) or a high-salt (4% NaCl) diet and divided into five groups: two control groups with a low-salt or a high-salt diet without angiotensin II infusion (saline infusion), and three angiotensin II groups (angiotensin II infusion, 10 or 50 ng/kg per min with high-salt diet, 50 ng/kg per min with low-salt diet, subcutaneously). The rats were kept on these regimes for 8 weeks. The blood pressure was measured every week. Functional and morphological alterations in the kidney were assessed at the end of the experiment

RESULTS

There were no differences in the arterial blood pressures of the five experimental groups. However, angiotensin II infusion increased the weights of the heart and aortic walls in a dose-dependent manner in the high-salt groups. There was also a dose-dependent increase in proteinuria, N-acetyl-beta-D-glucosaminidase activity (NAG) excretion, and additional glomerular and arterial injuries in the kidney, associated with angiotensin II infusion in the high-salt groups. In the rats given a higher dose of angiotensin II, the high-salt diet significantly increased the weights of the heart and aortic walls and exacerbated the renal function and morphological injuries, compared to the low-salt group. High-salt diet alone increased the kidney and heart weights. However, it did not significantly influence the results of the morphological and functional study. On the other hand, angiotensin II infusion on a low-salt diet showed a trend towards glomerular damage; however, the effects were small and not significant. Similarly, there were few effects of angiotensin II infusion on morphology and functional study on a low-salt diet

CONCLUSION

These data clearly show that a high-salt intake increases susceptibility of the kidney to injuries induced by low doses of angiotensin II in normotensive, uni-nephrectomized rats.

Regression of glomerular injury by kallikrein infusion in Dahl salt-sensitive rats is a bradykinin B2-receptor-mediated event

AIMS

We investigated whether kallikrein infusion attenuates renal injury in Dahl salt-sensitive rats with hypertension and assessed the role of bradykinin-nitric oxide axis in the renal protection using HOE-140, the bradykinin type-2 (B2) receptor specific antagonist.

METHODS

Subdepressor dose of purified rat urinary kallikrein (RUK) (400 ng/day) was continuously infused through the jugular vein by an osmotic mini-pump for 4 weeks in Dahl salt-sensitive (Dahl S) rats fed a high-salt (2% NaCl) diet.

RESULTS

Blood pressure increased in a time-dependent manner in Dahl S rats fed a high-salt diet. The RUK infusion did not influence the elevation of blood pressure in Dahl S rats. However, the RUK infusion significantly decreased urinary protein excretion, and increased glomerular filtration rate, as compared with untreated high-salt Dahl S rats. Morphological investigation disclosed that the RUK infusion significantly attenuated glomerulosclerosis and arterial and tubular injuries in the kidney of hypertensive Dahl S rats. The RUK infusion produced an increase in urinary excretions of nitric oxide and cyclic guanosine monophosphate. In addition, the RUK infusion enhanced the generation of nitric oxide from the kidney slices. The functional and morphological effects of the RUK infusion on the kidney were completely lessened by co-administration of the bradykinin B2-receptor antagonist, HOE-140.

CONCLUSION

Long-term infusion of subdepressor dose of rat urinary kallikrein attenuates functionally and morphologically the progression of renal injury in Dahl rats susceptible to salt-induced hypertension, and that the protection is mediated by stimulation of bradykinin B2 receptor.

Angiotensin II subtype-1 receptor antagonists improve hemodynamic and renal changes without affecting glucose metabolisms in genetic rat model of non-insulin-dependent diabetes mellitus

The Otsuka Long-Evans Tokushima Fatty (OLETF) rat is a new genetic model of non-insulin-dependent diabetes mellitus (NIDDM). We investigated whether treatment with an angiotensin II (ANGII) subtype-1 receptor antagonist delays the onset of NIDDM and attenuates diabetic nephropathy in the OLETF rat. OLETF rats fed a regular chow were treated with ANGII subtype-1 receptor antagonists (E4177 or TA606) for 22 weeks. Hemodynamic changes, glucose metabolism, and the effects on diabetic nephropathy were examined. Systolic blood pressure increased in OLETF rats in an age-dependent manner. OLETF rats exhibited increases in plasma concentrations of glucose and insulin and developed glucosuria at the age of 28 weeks. The changes in glucose metabolism were associated with proteinuria and an increase in urinary excretion of N-acetyl-beta-D-glucosaminidase (NAG). Morphologic investigation revealed nodular lesions in glomeruli in the OLETF rats. The ANGII receptor antagonist treatment abolished the blood pressure elevation. However, the treatment did not affect plasma glucose and insulin levels and did not significantly reduce glucosuria. Nodular lesions in glomeruli were not improved by the treatment. However, the receptor antagonists significantly reduced proteinuria and urinary NAG excretion. Multivariate analyses revealed that proteinuria was determined by systolic blood pressure, lipid metabolism, and glucose levels in plasma. ANGII subtype-1 antagonism does not improve glucose metabolism in the OLETF rat model of NIDDM, which has abnormalities in the glucose-uptake system. Blood pressure elevation and part of the proteinuria associated with NIDDM depends on the renin-angiotensin system rather than glucose metabolisms per se.

Angiotensin-Converting Enzyme Inhibition Delays Onset of Glucosuria With Regression of Renal Injuries in Genetic Rat Model of Non-Insulin-Dependent Diabetes Mellitus

BACKGROUND: The Otsuka Long-Evans Tokushima Fatty (OLETF) rat is a new genetic model of non-insulin-dependent diabetes mellitus (NIDDM). We investigated whether angiotensin inhibition influences the onset of NIDDM and brings about a regression of renal injury in diabetes mellitus. METHODS AND RESULTS: Six-week-old OLETF rats were treated with the angiotensin-converting enzyme (ACE) inhibitors imidapril or enalapril for 16 weeks. Systolic blood pressure is increased in an age-dependent manner in OLETF rats. In this study, the elevation in systolic blood pressure was dose-dependently reduced by ACE inhibitor treatment. In OLETF rats, plasma concentrations of insulin and glucose increased and the glucosuria occurred at the age of 22 weeks. Simultaneously, OLETF rats exhibited proteinuria and nodular lesions in glomeruli. The ACE inhibitor treatment almost completely reduced glucosuria, and also decreased plasma concentrations of insulin and glucose in OLETF rats. ACE inhibitor treatment lessened the proteinuria and attenuated morphologically the severity of nodular lesions in OLETF rats. Moreover, increases in plasminogen activator inhibitor 1 (PAI-1) in OLETF rats were reduced by the ACE inhibitor treatment, and the improvement of glomerular lesions was related to decreases of PAI-1 and angiotensin II levels in plasma but not to improvement of glucose metabolism. CONCLUSIONS: ACE inhibitors delay onset of NIDDM with attenuation of kidney injury. The regression of kidney lesions is probably due to angiotensin reductions but not to glucose metabolism per se. ACE inhibitor drug therapy may be useful in preventing NIDDM and the subsequent renal injury in patients with NIDDM.

Comparison between cilnidipine and nisoldipine with respect to effects on blood pressure and heart rate in hypertensive patients

Cilnidipine is a new and unique 1,4-dihydropyridine calcium antagonist that has both L-type and N-type voltage-dependent calcium channel blocking actions. We compared the effects of cilnidipine and another once-daily dihydropyridine calcium antagonist, nisoldipine, on 24-h blood pressure and heart rate in patients with essential hypertension. We enrolled 10 hypertensive outpatients [9 men and 1 woman; age, 55+/-3 yr (means+/-SEM)] in this study. Their ambulatory blood pressure and heart rate were monitored for 24 h at intervals of 30 min with a portable recorder (TM-2425) after 8 wk of treatment with cilnidipine (5 to 20 mg once daily) and after 8 wk of treatment with nisoldipine (5 to 20 mg once daily). The order of the two treatments was randomized. Blood pressure and heart rate measurements for a 24-h period were analyzed for four segments of the day: morning (06:00 to 11:30), afternoon (12:00 to 17:30), nighttime (18:00 to 23:30), and sleeping time (0:00 to 5:30). Blood pressure levels were similar during the two treatment periods for each 6-h segment of the day. Heart rate was significantly higher during treatment with nisoldipine than during treatment with cilnidipine in the morning segment [by 4.1+/-1.3 beats/min (p < 0.05)] and the afternoon segment [by 6.4+/-3.6 beats/min (p< 0.05)]. These results suggest that cilnidipine is effective as a once-daily antihypertensive agent and causes reflex tachycardia less than does nisoldipine.

Comparison of 24-hour blood pressure, heart rate, and autonomic nerve activity in hypertensive patients treated with cilnidipine or nifedipine retard

We compared the effects of cilnidipine and nifedipine retard on 24-h blood pressure (BP), heart rate (HR), and autonomic nerve activity in patients with essential hypertension. Cilnidipine is a novel and unique 1,4-dihydropyridine calcium antagonist that has the L-type and N-type voltage-dependent calcium channel-blocking action. Fourteen hypertensive outpatients (four men and 10 women; aged 64 +/- 2 years, mean +/- SEM) were enrolled in this study. Their ambulatory BP and electrocardiogram were monitored for 24 h at intervals of 30 min with a portable recorder after a 4-week drug-free period, after a 4-week treatment period with cilnidipine (5 or 10 mg once daily), and after a 4-week treatment period with nifedipine retard (10 or 20 mg twice daily). The order of the three periods was randomized. Autonomic nerve activity was evaluated by a power spectral analysis of HR variability, by using the high-frequency (HF) component as an index of parasympathetic nerve activity and the ratio of the low-frequency (LF) component to the HF component (LF/HF) as an index of sympathovagal balance. Cilnidipine and nifedipine retard significantly reduced the 24-h BP of these patients to similar extents (cilnidipine, -11 +/- 3/-6 +/- 1 mm Hg; nifedipine retard, -15 +/- 3/-6 +/- 2 mm Hg). Cilnidipine did not change the 24-h average HR, whereas nifedipine retard significantly increased it (+3.3 +/- 1.4 beats/min; p < 0.05). Nifedipine retard significantly increased the LF/HF ratio in the daytime and the nighttime. Such changes were limited to the daytime in the treatment period with cilnidipine. These results suggest that cilnidipine is effective as a once-daily antihypertensive agent and had less influence on autonomic nervous system and HR than did nifedipine retard.

Serum N-acetyl-beta-D-glucosaminidase activity in a genetic rat model of non-insulin-dependent diabetes mellitus

Serum N-acetyl-beta-D-glucosaminidase activity (NAG) is a possible predictor of vascular injury in hypertension. We assessed whether the activity of this enzyme reflects vascular damage in a genetic rat model of non-insulin-dependent diabetes mellitus (NIDDM) in humans. Otsuka Long-Evans Tokushima Fatty (OLETF) rats fed a regular chow were treated with the angiotensin converting enzyme (ACE) inhibitor imidapril for 16 wk. Systolic blood pressure increased in a time-dependent manner in the untreated OLETF rats as compared with that in the control Long-Evans Tokushima (LET) rats. The blood pressure elevation was associated with increases in cardiac and aortic weight. Imidapril treatment significantly attenuated the blood pressure elevation and reduced the increases in cardiac and aortic weight. The untreated OLETF rats had higher plasma glucose and insulin concentrations than did the LET rats and presented with glucosuria at the age of 22 wk. Imidapril treatment strikingly decreased plasma glucose levels and the glucosuria. Plasma insulin concentrations decreased, approaching those of the non-diabetic control LET rats. ACE inhibitor treatment attenuated the nodular lesions in the glomeruli of OLETF rats and improved the kidney function. Serum NAG activity increased significantly by 35% in the untreated rats; this increase was attenuated significantly by imidapril treatment. The reduction in serum NAG activity correlated with improvement in cardiovascular injury. In contrast, there were no changes in urinary NAG excretion in the three OLETF rat groups. In addition, NAG excretion did not correlate with indices of cardiovascular injury. These data suggest that serum NAG activity is useful in predicting injury in the cardiovascular system in rats with diabetes mellitus.

Long-term infusion of kallikrein attenuates renal injury in Dahl salt-sensitive rats

We investigated whether long-term infusion of kallikrein would attenuate renal injury in salt-induced hypertension in Dahl salt-sensitive (Dahl S) rats. A subdepressor dose of purified rat urinary kallikrein (RUK) (700 ng/day) was infused intravenously by an osmotic minipump for 4 weeks in male Dahl S rats fed a high-salt (2% NaCl) diet. This dose did not affect the time-dependent elevation of blood pressure. However, urinary protein excretion was significantly decreased, and the glomerular filtration rate was increased. These beneficial effects were reflected morphologically by an attenuation of the glomerulosclerotic lesions and tubular injury seen in the hypertensive Dahl S rats. The kallikrein infusion increased the urinary excretion of bradykinin and stimulated the excretion of cyclic GMP, suggesting that the kallikrein-kinin-prostaglandin and nitric oxide axes were enhanced by the RUK infusion. The alterations induced by such infusion were potentiated by the concomitant administration of the angiotensin converting enzyme inhibitor alacepril. These studies indicated that long-term replacement with rat tissue kallikrein attenuates renal injury in hypertensive Dahl S rats, and this is probably mediated by an enhanced function of the kallikrein-kinin-prostaglandin and nitric oxide systems.

The implication of renin-angiotensin system on renal injury seen in Dahl salt-sensitive rats

Angiotensin II (Ang II) progresses to remodeling of the cardiovascular system through nonhemodynamic as well as hemodynamic effects. There have been few data in vivo on whether subpressor concentration of Ang II is exerted to injure directly the cardiovascular system in hypertension. To test this hypothesis, we investigated, using Dahl salt-sensitive (Dahl S) rats, whether subpressor dose of Ang II progresses to cardiovascular injury observed in salt-induced hypertension. Recent studies have provided evidence that renin-angiotensin inhibition protects against renovascular injury in human hypertension as well as in experimental animals. Particularly in the case of Dahl salt-sensitive rats, a genetic model of volume-dependent hypertension in humans, they are likely to develop more severe arterial and renal injuries than those seen in spontaneously hypertensive rats with similar blood pressure levels. The mechanism of the susceptibility to hypertensive injuries is uncertain; however, renin-angiotensin inhibition significantly improved morphologic and functional injuries in the kidney of Dahl S rats. Conversely, subpressor dose of Ang II infusion exacerbated renal function and progressed to glomerulosclerotic lesions. Alterations of Ang II concentration in physiologic range influenced morphologic and functional injuries in Dahl S rats. Multivariate analysis revealed that activity of the renin-angiotensin system is an independent risk factor to glomerular injury in salt-induced hypertension. These data are in favor of the therapeutic strategy in human hypertension that inhibition of renin-angiotensin system is of value to produce beneficial effects of blood pressure reduction on organ injuries.

Thromboxane inhibition potentiates antihypertensive effects of alpha 1 adrenoceptor antagonists in the rat

We investigated the influence of the vascular and renal thromboxane system on the antihypertensive effects of the alpha 1 adrenoceptor antagonist (alpha 1 blocker) bunazosin in spontaneously hypertensive rats (SHR). SHR were treated for 2 weeks with the alpha 1, blocker bunazosin (0.5 mg/kg body weight/day). The systolic blood pressure immediately declined with bunazosin treatment, and then rose toward the level observed in untreated SHR. This antihypertensive effect was accompanied by a decrease in the ratio of prostacyclin to thromboxane A2 in the vascular wall and the kidney. A subdepressor dose of the thromboxane synthase inhibitor OKY-046 lessened the thromboxane generation during bunazosin treatment, and synergistically potentiated the antihypertensive action of the alpha 1 blocker. Such synergy was also observed between OKY-046 and prazosin, an alternative alpha 1 blocker, but not with amosulalol, an alpha 1 blocker having no quinazoline moiety. alpha 1 blockers with a quinazoline moiety dose-dependently stimulate thromboxane generation in cultured smooth muscle cells from SHR. These data indicate that alpha 1 blockers enhance thromboxane generation in the arterial wall and kidney, thereby contributing to the lessening of the antihypertensive effects observed during alpha 1 blocker treatment.

Endothelin-mediated effect of erythropoietin on blood pressure and renal hemodynamics in hypertensive rats

Erythropoietin (EPO) has been reported to induce hypertension in hemodialysis patients with family history of hypertension. In this study, to reveal the mechanism of EPO-induced hypertension, we examined the acute effect of EPO on blood pressure (BP) and renal hemodynamics in genetically hypertensive rats, and we also tested the effect of BQ-123, an endothelin ETA-receptor blocker, on EPO-induced changes in hemodynamics. Male spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY), aged 9-12 wk, were anesthetized, and BP was monitored through the carotid artery. Renal plasma flow (RPF) and glomerular filtration rate (GFR) were measured before and after an intravenous injection of EPO (1,000 U/kg body wt). In another group of SHR, BQ-123 was continuously infused (1.2 mg.kg body wt-1.h-1) during the experiments. The acute injections of EPO increased BP significantly in SHR in a dose-dependent manner, whereas WKY did not show a significant increase in BP after EPO injections. The effect of EPO on BP in SHR was blocked by BQ-123. In SHR, an acute injection of EPO decreased RPF significantly (from 1.78 +/- 0.16 to 1.49 +/- 0.18 ml.min-1.100 g body wt-1, P < 0.05) without a change in GFR, whereas WKY did not show significant changes in either RPF or GFR. The effect of EPO on RPF in SHR was completely blocked by BQ-123 (from 1.92 +/- 0.26 to 1.88 +/- 0.28 ml.min-1.100 g wt-1, NS). EPO caused a significant increase in plasma endothelin ET-1 in SHR (from 2.3 +/- 0.6 to 6.3 +/- 1.6 pg/ml, P < 0.05), but not in WKY. In conclusion, acute administration of EPO raised blood pressure and reduced RPF in SHR, and these vasoconstrictive effects of EPO are mediated via ETA receptors by an enhanced ET-1 release.

Successful erythropoietin treatment for severe anemia in nephrotic syndrome without renal dysfunction

A 62-year-old woman presented with nephrotic syndrome and severe anemia although the renal function was not impaired. Renal biopsy revealed the histology of membranoproliferative glomerulonephritis, and the proteinuria was resistant to steroid therapy. Iron deficiency, bleeding and other causes of anemia were ruled out, however, her serum erythropoietin level was inappropriately low. The anemia was rapidly corrected by administration of recombinant human erythropoietin. It is suggested that inappropriately low erythropoietin level, in part at least, accounts for the anemia in nephrotic syndrome. It is proposed that erythropoietin therapy should be taken into consideration for severe anemia in nephrotic syndrome even when the renal function is not impaired.

Hachimi-jio-gan extract protects the kidney from hypertensive injury in Dahl salt-sensitive rat

We investigated whether the Chinese herbal remedy, Hachimi-jio-gan extract, attenuates the renal injury seen in salt-induced hypertension in Dahl salt-sensitive (Dahl S) rats. Administration of this extract for 5 weeks dose-dependently decreased systolic blood pressure in Dahl S rats fed with a high-salt (2% NaCl) diet. This blood pressure reduction was associated with a decrease in cardiac mass and in thickness of the aortic wall. Urinary excretion of prostaglandin E2 was increased and glomerular filtration rate was improved with this treatment. Glomerulosclerosis and arterial injury in the kidney were morphologically improved. These data suggest that Hachimi-jio-gan extract exhibits an antihypertensive effect, which is associated with partial resolution of renal injury in salt-induced hypertension.

Hydrochlorothiazide Increases Efferent Glomerular Arteriolar Resistance in Spontaneously Hypertensive Rats

BACKGROUND: Micropuncture studies were performed to determine the intrarenal hemodynamic effects of two conventional antihypertensive agents, hydrochlorothiazide (HCTZ) and hydralazine (HYDR) alone and in combination. METHODS AND RESULTS: Male spontaneously hypertensive and normotensive Wistar Kyoto rats (19 weeks old) were treated for 3 weeks with vehicle (control), HCTZ (80 mg/kg/d), HYDR (5 mg/kg/d), or combined therapy (HCTZ 30 mg/kg/d and HYDR 2 mg/kg/d). Each treatment significantly reduced arterial pressure while effective renal plasma flow, glomerular filtration rate and single nephron glomerular filtration rate were unaffected by any treatment in either strain. In spontaneously hypertensive rats HCTZ decreased single nephron plasma flow (111 +/- 8 to 84 +/- 4 nL/min; P <.05) but, despite this reduction, glomerular pressure remained unchanged (51.4 +/- 0.7 to 52.1 +/- 0.8 mmHg) attributable to increased efferent glomerular resistance (1.58 +/- 0.14 to 2.11 +/- 0.12 10 U; P <.05). By contrast, HYDR increased single nephron plasma flow (to 147 +/- 8 nL/min; P <.01) and decreased efferent glomerular resistance (to 1.09 +/- 0.09 U; P <.05). Combined treatment produced responses similar to HCTZ when used alone, thereby nullifying the beneficial efferent glomerular resistance effects: single nephron plasma flow +/- fell (to 89 +/- 7 nL/min; P <.05) and efferent glomerular resistance increased (to 2.05 +/- 0.17 U; P <.05). In Wistar Kyoto rats, HCTZ and combined treatment had no effect. HCTZ alone induced glomerular ischemia that was associated with efferent glomerular arteriolar constriction in these spontaneously hypertensive rats. CONCLUSIONS: These findings provide a possible explanation for the lack of improved renal target-organ damage in controlled multicenter trials employing thiazide diuretics.

A new adenosine subtype-1 receptor antagonist, FK-838, attenuates salt-induced hypertension in Dahl salt-sensitive rats

We investigated the effects of the adenosine type-1 receptor antagonist FK-838 on salt-induced hypertension in Dahl-Sea salt-sensitive (Dahl S) rats. Dahl S rats fed a high-salt (4% NaCl) diet for 4 weeks were treated with FK-838 or hydrochlorothiazide for 4 weeks and alterations in kidney function and morphologic changes were assessed. FK-838 attenuated the development of hypertension in Dahl S rats, and caused a decrease in aortic weight in a dose dependent fashion. The adenosine antagonist did not produce any detectable metabolic disturbance. The blood pressure reduction by FK-838 was associated with attenuation of glomerular and arterial injury in the kidney. The renal protective effect of FK-838 treatment was associated with a reduction of plasma renin activity and plasma aldosterone concentration. In contrast, the thiazide diuretic, which produced almost the same blood pressure reduction as FK-838, did not attenuate renal damage. These data indicate that adenosine A1 receptor antagonism reduces salt-induced hypertension and the consequent renal injuries.

Possible linkage between renal injury and cardiac remodeling in Dahl salt-sensitive rats treated with the calcium channel antagonist benidipine

Interest in cardiovascular protection by calcium channel antagonists has grown over the past decade. We investigated the prevention of cardiac remodeling and renal injury by the long-acting calcium channel antagonist benidipine using 12 week-old Dahl salt-sensitive (Dahl S) rats fed a high-salt (4% NaCl) diet. Six-week benidipine treatment (10 mg/kg chow) decreased systolic blood pressure by 22% in Dahl S rats. This blood pressure reduction was associated with decreases in cardiac mass and weight of the aortic wall. Collagen content in the left ventricle tended to decline with benidipine treatment. In addition, glomerular filtration rate increased by 33% and arterial and glomerular lesions improved morphologically with this treatment. Regression of cardiac mass and collagen content in the left ventricle was due mainly to blood pressure reduction; however, collagen content in the low-pressure right ventricle was not only related to systemic blood pressure but to the severity of renal lesions. These data suggest that the calcium channel antagonist benidipine attenuates cardiac and renal injury in hypertensive Dahl S rats, and that part of the cardiac hypertrophy is due to a non-hemodynamic mechanism that might be responsible for, or be a consequence of, the lesions in the kidney.

Glomerular dynamics and morphology of aged spontaneously hypertensive rats. Effects of angiotensin-converting enzyme inhibition

Relationships between glomerular dynamics and renal injury, micropuncture and histological studies were assessed in 73 week-old normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats divided into untreated and angiotension-converting enzyme inhibitor-treated (quinapril; 3 mg/kg/day; for 3 weeks) groups. Urinary protein excretion (UPE) and histologic arteriolar (AIS) and glomerular (GIS) injury scores were determined. Mean arterial pressure (MAP) of untreated SHR was increased compared with WKY (200 +/- 6 vs 119 +/- 4 mm Hg; P < 0.01), effective renal plasma flow (ERPF) was reduced (1.47 +/- 0.21 vs 3.06 +/- 0.26 ml/min/per g; P > 0.01), and filtration fraction (FF) and total renal vascular resistance (RVR) of SHR were increased (P < 0.01). Single-nephron plasma flow (SNPF) of untreated SHR was decreased (174 +/- 17 vs 80 +/- 9 ml/min; P < 0.01), and single-nephron filtration fraction and afferent arteriolar resistance (RA) were increased (19.4 +/- 1.8 vs 30.0 +/- 2.5% and 1.90 +/- 0.25 vs 9.05 +/- 1.35 U, respectively; both P < 0.01). Despite reduced SNPF, glomerular capillary pressure (PG) increased (49.7 +/- 0.7 vs 53.8 +/- 1.3 mm Hg; P < 0.05), the result of efferent arteriolar constriction (1.15 +/- 0.18 vs 2.84 +/- 0.36 U; P < 0.01). Untreated SHR had higher UPE (13.9 +/- 1.5 vs 42.8 +/- 3.2; mg/100 g per day; P < 0.01) and GIS and AIS scores than WKY (4.3 +/- 1.1 vs 64.3 +/- 8.4 and 16.6 +/- 3.1 vs 96.3 +/- 14.4; both P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Subpressor dose of angiotensin II increases susceptibility to the haemodynamic injury of blood pressure in Dahl salt-sensitive rats

OBJECTIVE

To investigate the effects of subpressor doses of angiotensin II (Ang II) on the progression of renal injuries in Dahl salt-sensitive (Dahl-S) rats with hypertension.

METHODS

Rats were fed a high-salt (4% NaCl) diet and given an Ang II infusion (10 or 50 ng/kg per min, subcutaneously) for 4 weeks.

RESULTS

The plasma Ang II concentration achieved in the high-dose Ang II infusion was lower than that in low-salt (0.3% NaCl) normotensive rats. The Ang II infusion did not affect systolic blood pressure, cardiac hypertrophy or weight of thoracic aorta. However, the high-dose Ang II infusion increased proteinuria by 58%, enhanced the urinary N-acetyl-beta-D-glucosaminase index by 77% and reduced the glomerular filtration rate by 37%. The impaired renal function was associated with a progression of glomerulosclerotic lesions. Neither tubular nor arterial lesions were exacerbated. The infusion did not influence prostacyclin production or urinary cyclic GMP excretion.

CONCLUSION

A subpressor dose of Ang II infusion impairs renal function with progression of glomerulosclerosis, and these alterations may be due to increased susceptibility of the glomerulus in Dahl-S rats to Ang II-induced injuries. Such a mechanism might underlie a predisposition to hypertension-induced organ damage seen in Dahl-S rats with salt-induced hypertension.

Intrarenal hemodynamics in low- and high-output cardiac failure in rats

Cardiac failure is multifactorial in causation, and the underlying physiologic mechanisms are variable, yet their renal effects have been considered more homogeneous. To investigate and compare the intrarenal hemodynamic characteristics in two experimental types (low- and high-output) of cardiac failure, renal micropuncture studies were performed in rats after myocardial infarction (MI) and arteriovenous fistula, respectively. Myocardial infarction was produced by ligation of the left main coronary artery and arteriovenous fistula by direct puncture of the aorta and inferior vena cava below the renal arteries. Pressures and interrenal and glomerular dynamics were obtained using classic micropuncture techniques. Both forms of cardiac failure were characterized by elevated left ventricular end-diastolic pressure (LVEDP), reduced mean arterial pressure, and increased cardiac mass. Left ventricular end-diastolic pressure was higher in MI rats, and effective renal plasma flow (ERPF) tended to be reduced in both forms of cardiac failure. There were no apparent differences in effective renal plasma flow between two models. In addition, single-nephron plasma flow and single-nephron glomerular filtration rate were reduced, and single-nephron filtration fraction and glomerular capillary pressure (PG) were increased in both models. These changes were associated with higher afferent and efferent arteriolar resistances and lower ultrafiltration coefficients. Despite these similarities, PG was higher in MI rats, yet LVEDP correlated directly with PG (r = 0.73; P < 0.001) and efferent arteriolar resistances (r = 0.72; P < 0.01). Therefore, although systemic arterial pressure and effective renal plasma flow were similar in both models of cardiac failure, PG was significantly higher in MI rats with higher LVEDP than in arteriovenous fistula rats.(ABSTRACT TRUNCATED AT 250 WORDS)

New dihydropyridine calcium channel antagonist, pranidipine, attenuates hypertensive renal injury in Dahl salt-sensitive rats

Interest in the cardiovascular protective effects of calcium channel antagonists has increased in the past decade. We investigated prevention of vascular wall remodeling by the long-acting calcium channel antagonist pranidipine in 12-week-old Dahl salt-sensitive (SS) rats with high-salt-induced (4% NaCl) hypertension. Six-week pranidipine treatment (60 mg/kg chow) decreased systolic blood pressure (SBP) by 22% in SS rats. This BP reduction was associated with decreases in cardiac mass and weight of the aortic wall. Glomerular filtration rate (GFR) was increased by 33%, but this did not lead to a decrease in urinary protein or NAG excretion. Morphologic investigation demonstrated striking resolution of arterial injury (medial necrosis and/or hyperplasia, inflammatory cell infiltration, and thrombus formation) by 87% after pranidipine treatment. Glomerular sclerosis was also attenuated by 61%, whereas tubular injury was improved by only 28%. These morphologic changes were reflected in the findings that the capacity of kidney homogenate for generating lipid peroxides was significantly decreased and that collagen levels and pattern type became similar to those of normotensive salt-resistant (SR) rats. Pranidipine also attenuated hypertensive vasculopathy in small arteries of the middle cerebral arteries. Thus, the calcium channel antagonist pranidipine can attenuate the vascular injury that occurs in salt-induced hypertension, a promising property that implicates its clinical usage, particularly in essential hypertension with cardiovascular complications.

Vasoconstrictors and renal protection induced by beta 1-selective adrenoceptor antagonist bisoprolol

We investigated the role of the vasoconstrictors endothelin-1 (ET-1) and thromboxane in renal protection by the beta 1-selective adrenoceptor antagonist, bisoprolol, in Dahl salt-sensitive rats (Dahl S) and salt-resistant rats (Dahl R). Six-week bisoprolol treatment (20 mg/kg chow) reduced systolic blood pressure (SBP) by 14% in Dahl S rats fed a high-salt (4% NaCl) diet. This BP reduction was accompanied by a decrease in aortic wall thickness. ET-1 and thromboxane released from renal cortex was significantly decreased by 17 and 30% with bisoprolol, respectively. Other prostaglandin synthesis was unaffected. Renal function such as proteinuria, N-acetyl-beta-D-glucosaminidase (NAG) excretion, and glomerular filtration rate (GFR) was not influenced by bisoprolol. Morphologic investigation showed that bisoprolol significantly improved glomerular sclerosis by 29% and attenuated arterial damage by 71%, although tubular injury was not affected. The more severe the glomerulosclerotic lesions, the greater the generation of thromboxane and ET. The arterial lesions were positively correlated to thromboxane generation. These data indicate that long-term bisoprolol treatment reduces vasoconstrictive ET-1 and thromboxane generation and that these alterations may be partly responsible for the amelioration of glomerular and arterial injury in Dahl S rats.

Effects of ANG-converting enzyme and alpha 1-adrenoceptor inhibition on intrarenal hemodynamics in SHR

To investigate the prolonged effects of angiotensin-converting enzyme (ACE) inhibition and alpha 1-adrenoceptor blockade on intrarenal hemodynamics, whole kidney and renal micropuncture studies were performed in male 21-wk-old Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats treated for 3 wk with quinapril (3 mg/kg), terazosin (1 mg/kg), or in their combination (quinapril 1.5 mg/kg and terazosin 0.5 mg/kg). In WKY, only quinapril significantly reduced mean arterial pressure (MAP) associated with reduced afferent arteriolar resistance; there were no other significant changes. In contrast, all treatments similarly decreased MAP in SHR. Quinapril increased renal plasma flow and decreased filtration fraction. With respect to intrarenal hemodynamics, quinapril increased single-nephron plasma flow and reduced glomerular capillary pressure (from 53.1 to 47.8 mmHg; P < 0.01), associated with reduced afferent (from 4.80 to 3.17 10(10)dyn.s.cm-5; P < 0.01) and efferent (from 1.70 to 1.17 10(10)dyn.s.cm-5; P < 0.01) arteriolar resistances, and increased ultrafiltration coefficient (from 0.037 to 0.052 nl.s-1.mmHg-1; P < 0.05). Terazosin only reduced arteriolar resistance. The combined treatment attenuated either agent's independent effects on glomerular hemodynamics. These data demonstrate that prolonged ACE and adrenergic inhibition therapy alone or in combination produce different effects than when given by vein, suggesting that prolonged renopressor system inhibition may be more effective than adrenergic in SHR.

Antihypertensive effect of interleukin-2 in salt-sensitive Dahl rats

We investigated the effects of interleukin-2, which stimulates the proliferation and maturation of thymus-derived lymphocytes, on hypertension and organ injuries in genetically hypertensive rats. Interleukin-2 (5 x 10(4) U/kg body wt) was subcutaneously injected into Dahl salt-sensitive rats fed a 4% NaCl diet and spontaneously hypertensive rats once a week for 10 weeks. The effects on blood pressure, cardiovascular hypertrophy, and renal function were evaluated. Interleukin-2 treatment lowered blood pressure in Dahl salt-sensitive rats (162 versus 187 mm Hg, P < .005). This antihypertensive effect was associated with an increase in glomerular filtration rate (589 versus 428 mL/d per 100 g body weight, P < .005) and reduction in cardiac weight (268 versus 305 mg/100 g body weight, P < .05). Interleukin-2 also alleviated the marked glomerular sclerosis in Dahl salt-sensitive rats (glomerular injury score, 151 versus 220; P < .001). In contrast, interleukin-2 did not affect the development of hypertension or organ injuries in spontaneously hypertensive rats. Histologically, glomerular and arterial lesions of the kidney were much less marked in spontaneously hypertensive rats than in Dahl salt-sensitive rats. These data indicate that interleukin-2 ameliorates the development of hypertension and cardiac and renal injuries in Dahl salt-sensitive rats.

De novo synthesis of phospholipase A2 and prostacyclin production by proliferating rat smooth muscle cells

We investigated the role of phospholipase A2 (PLA2) in cell cycle-dependent alterations of endogenous prostacyclin (PGI2) synthesis in aortic smooth muscle cells in culture (VSMC) from Wistar Kyoto rats. Randomly cycling VSMC generated more PGI2 than the stationary cells. Cell cycle analysis showed that PGI2 production capacity was increased from the G0/G1 through the early DNA synthetic (S) phases. Enzyme analysis revealed that, although there were different mechanisms underlying this increase in the PGI2 production during the G0/G1, the peak at 4 hours coincided with a sharp increase in PLA2 activity. This increase in PLA2 activity was preceded by an increased expression of functional PLA2 messenger RNA, and protein synthesis inhibition prevented most of the increase in PGI2 production at 4 hours. These data indicate that endogenous PGI2 generation is mainly increased during the G0/G1 period and that this event is secondary to de novo synthesis of PLA2 and probably, at least in part, to cyclooxygenase induction. This mechanism provides a negative feedback regulating VSMC proliferation.

Inhibition of protein synthesis and antiproliferative effect of the angiotensin converting enzyme inhibitor trandolaprilat in rat vascular smooth muscle cells

OBJECTIVE

To investigate the effect of the angiotensin converting enzyme (ACE) inhibitor trandolaprilat on vascular smooth muscle cell growth, and to analyse its mechanism of action.

DESIGN

Aortic vascular smooth muscle cells (VSMC) from Wistar-Kyoto rats were cultured, and cell proliferation was analysed using a cell synchrony technique.

METHODS

Proliferative activity was assessed by [3H]-thymidine uptake and doubling time. Protein synthesis was assessed by [3H]-leucine incorporation. Actin formation was measured using sodium dodecylsulphate-polyacrylamide slab gel electrophoresis and a densitometric assay. The effect of trandolaprilat on translational protein synthesis was also examined using the cell-free protein synthesis system of reticulocyte lysate and messenger RNA from VSMC.

RESULTS

Trandolaprilat decreased [3H]-thymidine uptake and increased the doubling time of randomly cycling VSMC. The cell synchrony study revealed that this antiproliferative effect was due to increased transition time from S to G2-M. Decreased cell cycle progression during G2-M was reflected by inhibition of cellular protein synthesis during this period. Cellular protein in randomly cycling VSMC was also decreased by trandolaprilat. This decreased protein synthesis was probably produced by inhibition of RNA translation.

CONCLUSIONS

The ACE inhibitor trandolaprilat reduces VSMC proliferation by lengthening the G2-M phase of the cell cycle, and produces a decrease in cellular protein content. This effect is probably mediated by inhibition of protein synthesis at the translational level.

Possible radical scavenging properties of cicletanine and renal protection in Dahl salt sensitive rats

Much interest in cicletanine, a novel antihypertensive drug, has grown because it uniquely stimulates prostacyclin (PGI2) production and may, thereby, provide further cardiovascular protection. We postulated that cicletanine may be an antioxidant, and assessed its ability to protect the kidney in Dahl salt-sensitive (Dahl S) rats on a high salt diet. Cicletanine eradicated in vitro a stable radical, DPPH, and decreased the lipid peroxidation both in rat brain homogenate and in a xanthine-xanthine oxidase (X-XOD) superoxide generating system. Furthermore, cicletanine attenuated the inhibition of PGI2 synthase activity by 15HPETE. However, cicletanine did not exhibit superoxide dismutase-like activity in X-XOD system, suggesting that it behaves primarily as a hydroxy radical scavenger. A 6 week cicletanine treatment reduced blood pressure in Dahl S rats fed a high salt diet, and ameliorated functional and morphological injury to the kidney. This attenuation of glomerular sclerosis correlated with the attenuation of lipid peroxidation in the kidney homogenate. These data indicate that cicletanine is an antioxidant that protects the kidney from salt-induced hypertension in Dahl salt-sensitive strain rats.

Genetic predisposition to hypertension facilitates blood pressure elevation in hemodialysis patients treated with erythropoietin

PURPOSE

This study investigated the hypothesis that a genetic predisposition to hypertension is involved in the etiology of the elevation in blood pressure induced by human recombinant erythropoietin (rHuEPO).

PATIENTS AND METHODS

Blood pressure changes after 10 weeks of treatment with rHuEPO were compared between 26 patients with a positive family history of hypertension and 27 with a negative family history.

RESULTS

Mean blood pressure was significantly increased in patients with a positive family history of hypertension (+8.8 mm Hg, p < 0.001). In contrast, the change was not significant in those whose family history was negative (+1.8 mm Hg, not significant). The mean blood pressure of 14 of 26 patients with a positive family history of hypertension increased by more than 10%, whereas such an increase occurred in only 2 of 27 patients with a negative family history (p < 0.001). The two groups were similar in terms of the total dose of rHuEPO given, the degree to which their anemia improved, and their basal blood pressures.

CONCLUSION

It appears that hemodialysis patients with a positive family history of hypertension are susceptible to developing hypertension during treatment with rHuEPO.