3332Exercise training ameliorates vasodilator capacity of coronary microvessels in patients with vasospastic angina - A new therapeutic approach for the coronary functional disorder

Background

We have recently demonstrated that coronary vasospasm could develop in both epicardial coronary arteries and intramuscular coronary microvessels in patients with vasospastic angina (VSA). However, it remains to be examined whether vasodilator capacity of coronary microvessels is impaired in VSA patients and if so, whether exercise training could ameliorate vasodilator capacity of coronary microvessels on the top of calcium channel blockers. The effectiveness of exercise training is established for organic coronary artery disease but remained to be examined for VSA.

Purpose

We thus examined whether vasodilator capacity of coronary microvessels is impaired in VSA patients without organic coronary stenosis using an adenosine-stress dynamic computed tomography perfusion (CTP) that can measure absolute value of myocardial blood flow (MBF). We also examined whether exercise training ameliorates not only vasodilator capacity of coronary microvessels but also exercise capacity and frequency of angina attack.

Methods

In the first protocol, we measured MBF using CTP in consecutive 32 VSA patients with acetylcholine-induced diffuse coronary spasm in the left anterior descending coronary arteries (LAD) and 12 non-VSA controls. In the second protocol, we conducted a randomized controlled trial (RCT; Exercise VSA trial, UMIN: ehz745.008423996), where 20 VSA patients were randomly assigned to either exercise group (Ex group: supervised exercise training session for 30-min using bicycle ergometer, once/week at the hospital and more than 3 times/week at home) or non-exercise group (Non-Ex group) (n=10 each) (Figure A). Before and 3 months after exercise training, we measured MBF with adenosine-stress dynamic CTP and peak VO2 by cardiopulmonary exercise tests, and also assessed angina attack with Seattle Angina Questionnaire (SAQ).

Results

In the first protocol, CTP showed that adenosine-stress MBF was significantly decreased in the VSA group compared with the non-VSA group (VSA, 137.2±6.6 vs. Non-VSA, 174.4±10.7 ml/100g/min, P<0.01) (Figure B), although patient characteristics were comparable between the 2 groups. In the second protocol, exercise training was performed safely in all patients, and RCT showed that MBF was significantly increased in the Ex group compared with the non-Ex group (Figures C, D), although patient characteristics were also comparable between the 2 groups. Furthermore, peak VO2 was significantly increased in the Ex group compared with the non-Ex group (Figure E), and frequency of angina was significantly decreased in the Ex group compared with the non-Ex group (Figure F). Finally, there was a significant positive correlation between the extents of the changes in peak VO2 and the SAQ score for angina frequency in the Ex group (P<0.01, R=0.67).

Figures

Conclusions

These results provide the first evidence that vasodilator capacity of coronary microvessels is impaired in VSA patients, which can be ameliorated by exercise training.

Effect of radiation monitoring method and formula differences on estimated physician dose during percutaneous coronary intervention

BACKGROUND

Currently, one or two dosimeters are used to monitor radiation exposure in most cardiac laboratories. In addition, several different formulas are used to convert exposure data into an effective dose (ED).

PURPOSE

To clarify the effect of monitoring methods and formula selection on the estimated ED for physicians during percutaneous coronary interventions (PCIs).

MATERIAL AND METHODS

The ED of physicians during cardiac catheterization was determined using an optically stimulated luminescence dosimeter (Luxel badge). Two Luxel badges were worn: one beneath a personal lead apron (0.35-mm lead equivalent) at the chest and one outside of the apron at the neck.

RESULTS

The difference in the average ED of seven physicians was approximately fivefold (range 1.13-5.43 mSv/year) using the six different formulas in the clinical evaluation. The estimated physician ED differed markedly according to both the monitoring method and formula selected.

CONCLUSION

ED estimation is dependent on both the monitoring method and the formula used. Therefore, it is important that comparisons among laboratories are based on the same monitoring method and same formula for calculating the ED.

Influence of the target vessel on the location and area of maximum skin dose during percutaneous coronary intervention

BACKGROUND

A number of cases involving radiation-associated patient skin injury attributable to percutaneous coronary intervention (PCI) have been reported. Knowledge of the location and area of the patient's maximum skin dose (MSD) in PCI is necessary to reduce the risk of skin injury.

PURPOSE

To determine the location and area of the MSD in PCI, and separately analyze the effects of different target vessels.

MATERIAL AND METHODS

197 consecutive PCI procedures were studied, and the location and area of the MSD were calculated by a skin-dose mapping software program: Caregraph. The target vessels of the PCI procedures were divided into four groups based on the American Heart Association (AHA) classification.

RESULTS

The sites of the MSD for AHA #1-3, AHA #4, and AHA #11-15 were located mainly on the right back skin, the lower right or center back skin, and the upper back skin areas, respectively, whereas the MSD sites for the AHA #5-10 PCI were widely spread. The MSD area for the AHA #4 PCI was larger than that for the AHA #11-15 PCI (P<0.0001).

CONCLUSION

Although the radiation associated with PCI can be widely spread and variable, we observed a tendency regarding the location and area of the MSD when we separately analyzed the data for different target vessels. We recommend the use of a smaller radiation field size and the elimination of overlapping fields during PCI.

Feasibility of rapid-sequence 31P magnetic resonance spectroscopy in cardiac patients

PURPOSE

To determine the clinical feasibility of rapid-sequence phosphorus-31 magnetic resonance spectroscopy (31P-MRS) of the heart with cardiac patients using a 1.5T clinical MR system.

MATERIAL AND METHODS

Twenty cardiac patients, i.e. dilated cardiomyopathy (DCM) 13 cases, hypertrophic cardiomyopathy (HCM) 3 cases, hypertensive heart diseases (HHD) 3 cases, and aortic regurgitation (AR) 1 case were examined using rapid cardiac 31P-MRS. Complete three-dimensional localization was performed using a two-dimensional phosphorus chemical-shift imaging sequence in combination with 30-mm axial slice-selective excitation. The rapid-sequence 31P-MRS procedure was phase encoded in arrays of 8 x 8 steps with an average of 4 acquisitions. The total examination time, including proton imaging and shimming, for the rapid cardiac 31P-MRS procedure, ranged from 10 to 15 min, depending on the heart rate. Student's t test was used to compare creatine phosphate (PCr)/adenosine triphosphate (ATP) ratios from the cardiac patients with those of the control subjects (n = 13).

RESULTS

The myocardial PCr/ATP ratio obtained by rapid 31P-MRS was significantly lower (P < 0.001) in DCM patients (1.82 +/- 0.33, mean +/- SD), and in patients with global myocardial dysfunction (combined data for 20 patients: 1.89 +/- 0.32) than in normal volunteers (2.96 +/- 0.59). These results are similar to previous studies.

CONCLUSION

Rapid-sequence 31P-MRS may be a valid diagnostic tool for patients with cardiac disease.

Rapid-sequence phosphorus-31 magnetic resonance spectroscopy of the human heart using a 1.5-T clinical system

PURPOSE

To compare a 'standard' slow phosphorus-31 magnetic resonance spectroscopy (31P-MRS) sequence with two faster sequences in phantoms and healthy volunteers using a 1.5-T clinical system.

MATERIAL AND METHODS

Complete 3D localization was performed using a 2D phosphorus chemical-shift imaging sequence in combination with 30-mm axial slice-selective excitation. Two 31P-MRS rapid sequences (RS8-4: 8 x 8 phase-encoding, with an average of 4 acquisitions, and RS16-1: 16 x 16 phase-encoding, 1 acquisition) were compared with the standard sequence (StdP: 16 x 16 phase-encoding, with an average of 8 acquisitions) in phantom and healthy volunteers.

RESULTS

Acquisition time for the 31P-MRS procedure with StdP, RS8-4, and RS16-1 in the healthy volunteer studies ranged from 30 to 45, 3 to 5, and 3 to 5 minutes, respectively. Metabolite measurements of healthy volunteers obtained from 31P-MRS using RS8-4 correlated with values obtained using StdP (PCr r2=0.63, P<0.001; ATP r=0.41, P<0.01 and PCr/ATP ratio r2=0.25, P<0.05). There was no correlation between StdP and RS16-1 for either ATP or the PCr/ATP ratio (r2=0.03, P=0.60, and r2=0.11, p=0.26, respectively). Reproducibility (intensity of phosphorus signal) with RS16-1 was worse than that of RS8-4 or StdP.

CONCLUSION

31P-MRS using RS8-4 may be a valid diagnostic tool for patients with cardiac diseases.

Effects of hypothermia on neonatal hypoxic-ischemic brain injury in the rat: phosphorylation of Akt, activation of caspase-3-like protease

Neuroprotective mechanisms of hypothermia have not been clearly established especially in the immature brain. To investigate the effect of hypothermia on cell death and cell survival signal pathways, we studied caspase-3-like activity and activation of Akt in a rat model of neonatal hypoxic-ischemic (H-I) brain injury. Seven-day-old rats underwent a combination of left common carotid artery ligation and exposure to 8% O(2) for 1-h (n=32). During recovery, the body temperature was reduced to 30 degrees C for 24 h in 16 animals, but was kept at 37 degrees C in 16 animals. Post-ischemic hypothermia was shown to diminish the caspase-3-like activity compared to normothermia at 6 and 24 h after H-I. Phospho-Akt was increased during the early reperfusion period after H-I in the normothermia group, but hypothermia rather decreased this enhanced phosphorylation of Akt following H-I. These results indicated that hypothermia may have some depressant effects on both cell death and cell survival signal pathways, and that Akt conceivably may not play a major role in the neuroprotective effect of hypothermia in the immature brain.

[Effects of CS-866, an angiotensin II receptor antagonist, in 5/6 nephrectomized spontaneously hypertensive rats]

To assess the chronic antihypertensive and renal protective effects of the specific angiotensin II receptor antagonist, CS-866, in the remnant kidney model of chronic renal failure, we administered it alone or in combination with temocapril, an angiotensin converting enzyme inhibitor, to 5/6 nephrectomized spontaneously hypertensive rats (SHR) for 8 weeks. At the age of 10 weeks, 5/6 nephrectomized SHR were allocated to receive two doses of CS-866 (CS-3; 3 mg/kg/day, or CS-10; 10 mg/kg/day), temocapril (TEM; 10 mg/kg/day), a combination of CS-866 (3 mg/kg/day) and temocapril (10 mg/kg/day) or the vehicle alone via oral gavage for 8 weeks. Systolic blood pressure (SBP) and urinary protein excretion (UprotV) were measured every two weeks. At the age of 18 weeks, the rats were decapitated and the blood, remnant kidney, aorta and heart were collected and used for biochemical measurements and histopathological studies. There was no significant difference in body weight among the groups during the study. All drug treatments significantly reduced SBP, UprotV, glomerular sclerosis index (GSI), relative interstitial volume (RIV) and the heart weight to body weight ratio. The hypotensive effects were in the order of combination therapy > CS-10 = TEM > CS-3. For correlational analysis, we used values for SBP and UprotV derived from the average of values in rats over the age of 12 weeks through 18 weeks. UprotV, GSI and RIV were found to be highly correlated with SBP among the individual rats pooled from all groups (r = 0.511, r = 0.754, r = 0.817, respectively) and the correlation was maintained among the group means (r = 0.945, r = 0.989, r = 0.918, respectively). Furthermore, the heart weight to body weight ratio was found to be highly correlated with SBP among the individual rats pooled from all groups (r = 0.923) and the correlation was maintained among the group means (r = 0.996). We conclude that organ protective effects of CS-866, TEM, or combination therapy are closely related to the magnitude of their antihypertensive effects.

Renal protective effects of chronic exercise and antihypertensive therapy in hypertensive rats with chronic renal failure

OBJECTIVES

Patients with chronic renal failure are restricted to mild physical activity and tend to a lack of exercise. However, there have been few reports regarding the influence of chronic exercise on the progression of renal disease. Similarly, there are few animal models concerned with the effect of exercise training on improving renal function. Therefore, we assessed the renal effects of moderate chronic treadmill exercise in a remnant kidney model of spontaneously hypertensive rats (SHR) with chronic renal failure. We also assessed the effects of exercise and antihypertensive therapy on renal function.

DESIGN AND METHODS

Eight-week-old SHR were subjected to 5/6 nephrectomy by removal of the left kidney and excision of two-thirds of the right kidney. The rats were divided into four groups: (i) no exercise (Non-EX); (ii) moderate exercise with treadmill running (20 m/min, 0 grade incline for 60 min) (EX); (iii) EX with an angiotensin converting enzyme (ACE) inhibitor, enalapril (2 mg/kg per day, i.p.); and (iv) EX with an angiotensin receptor antagonist, losartan (5 mg/kg per day, i.p.), for 4 weeks.

RESULTS

Chronic EX significantly attenuated the increase in proteinuria (P < 0.01) and significantly protected against increases in the index of glomerular sclerosis (IGS). Both enalapril and losartan with EX significantly decreased blood pressure (P < 0.001), and further decreased the IGS. In the stepwise multiple regression analysis, only antihypertensive drug remained in the model as a significant predictor of IGS (P < 0.0001). In contrast, exercise, antihypertensive drug and mean systolic blood pressure (weeks 1-4) remained in the model as a significant predictors of mean proteinuria (weeks 1-4) (all P < 0.0001).

CONCLUSIONS

These results suggest that exercise does not worsen renal function and has renal-protective effects in this model of rats. Moreover, the antihypertensive therapy has additional renal-protective effects in this model of rats.

Post-ischemic hypothermia blocks caspase-3 activation in the newborn rat brain after hypoxia-ischemia

The effects of hypothermia on caspase-3 activation were investigated in the newborn rat brain after hypoxia-ischemia (HI). Intense caspase-3 activation was observed in the control brains after HI, but this activation was significantly reduced by postischemic hypothermia. These findings suggest that the inhibition of caspase-3 activation may be an interventional point underlying the neuroprotective effect of hypothermia in neonates.

Nonselective endothelin receptor antagonist initiated soon after the onset of myocardial infarction may deteriorate 24-hour survival

To investigate the effects of endothelin blockade initiated immediately after the onset of myocardial infarction on survival and left ventricular remodeling, treatment with the nonselective receptor antagonist TAK-044 (n = 22) or saline (n = 19) for 3 weeks was initiated immediately after coronary ligation in rats. The 24-h survival rate was significantly lower in the TAK-044 group than in the saline group. The systolic blood pressure 24 h after the onset of myocardial infarction was similar in the saline and TAK-044 groups, although it was significantly lower in the TAK-044 group during the 3-week protocol. Heart weight/tibial length was significantly increased in the TAK-044 group compared with the saline group. As all deaths in the TAK-044 group occurred within 24 h after myocardial infarction, we performed additional experiments using a separate group of rats 12-16 h after myocardial infarction. Plasma and myocardial endothelin-1 levels were significantly increased, and a bolus injection of TAK-044 significantly reduced left ventricular dP/dtmax in these rats that had had a myocardial infarction compared with sham-operated rats. Endothelin receptor blockade initiated immediately after the onset of myocardial infarction may deteriorate acute-phase survival and left ventricular remodeling. Inhibition of the positive inotropic action of endothlin-1 may partially explain the increased 24-h mortality.

Changes in serum hypoxanthine levels by exercise in obese subjects

To study on effect of obesity on changes in serum hypoxanthine with exercise, exercise stress testing with treadmill was performed on 7 obese subjects (body mass index [BMI], 30.6 +/- 3.2 kg/m(2)) and 16 healthy volunteers (BMI, 21.5 +/- 2.10 kg/m(2)). Expiratory gas analysis during exercise showed that peak Vo(2) was significantly lower in the obese group than in the control group (28.1 +/- 4.0 v 37.1 +/- 4.7 mL/kg/min; P <.001). Furthermore, the obese group had lower anaerobic threshold (AT) values (P <.005), respiratory quotient at AT (P =.003), and exercise capacity reserve (P =.002) than the control group. Baseline serum hypoxanthine levels were significantly higher in the obese group than in the control group (3.46 +/- 3.70 v 1.23 +/- 1.16 micromol/L; P <.05). Exercise induced a pronounced increase in serum hypoxanthine level in the obese group compared with the control group (10.65 +/- 6.81 v 43.86 +/- 4.56 micromol/L; P <.01). Serum levels of uric acid before and after load were also higher in the obese group than in the control group (404 +/- 43 v 302 +/- 77 micromol/L; P <.005). A pronounced increase in hypoxanthine with exercise may result in organ damage caused by free radicals, and intermittent training from mild intensity may be less hazardous for exercise treatment of obesity.

Effects of troglitazone and temocapril in spontaneously hypertensive rats with chronic renal failure

OBJECTIVE

The insulin resistance state is common in humans and animals with chronic renal failure. We investigated the effects of troglitazone, an insulin sensitizer, on blood pressure and nephropathy in the remnant kidney model of spontaneously hypertensive rats (SHR).

METHODS

Eight-week-old male SHR were subjected to five-sixth nephrectomy. At the age of 10 weeks, the rats were randomly allocated to groups that received troglitazone (70 mg/kg per day); the angiotensin converting enzyme inhibitor temocapril (10 mg/kg per day); troglitazone (70 mg/kg per day) plus temocapril (10 mg/kg per day), or a vehicle alone as an untreated control group. Systolic blood pressure (SBP) and urinary protein excretion were measured every 2 weeks. At the age of 22 weeks, biochemical measurements and histological examination were performed.

RESULTS

Blood glucose, glycosylated hemoglobin and body weight were similar in the four groups. SBP, serum creatinine and glomerular sclerosis index were significantly reduced in all treated groups compared with those in the control group. Urinary protein excretion, glomerular volume and aortic media thickness were significantly decreased in temocapril-treated rats and troglitazone plus temocapril-treated rats compared with those in control rats. Although antihypertensive effects of troglitazone were minute compared with those of temocapril or troglitazone plus temocapril, there was no significant difference between the glomerular sclerosis indices in these three drug-treated groups.

CONCLUSIONS

The results suggest that troglitazone has renoprotective effects in this rat model. These effects might be due to the inhibition of growth factors rather than to the minute hypotensive effect, although the mechanism remains to be elucidated.

Marked improvement of neuropsychological impairment in a patient with chronic obstructive pulmonary disease after lung volume reduction surgery

This paper reports a case of a 71-year-old pulmonary emphysema patient with neuropsychological impairments that were markedly improved 6 months after he underwent lung volume reduction surgery (LVRS). He also underwent pulmonary rehabilitation before and after surgery. He was suspected of having memory impairment and attention disorder when he was referred for rehabilitation. The neuropsychologic test showed a general cognitive impairment, attention disorder, and verbal memory impairment. Magnetic resonance imaging showed moderate atrophy of the left hippocampal area, cortex, and lacunae infarction in the periventricular area. Interestingly, scores of the neuropsychologic test, as well as severity of dyspnea and lung function, remarkably improved 6 months after LVRS. These results suggested that the neuropsychological impairments in pulmonary emphysema patients can be improved after lung reduction surgery.

Rehabilitating patients with hepatopulmonary syndrome using living-related orthotopic liver transplant: a case report

The objective of this study was to rehabilitate a patient with hepatopulmonary syndrome (HPS) who underwent living-related orthotopic liver transplantation (LT). HPS is rare; it presents severe complication in patients with liver disease. A 17-year-old woman with HPS developed portal hypertension after undergoing Kasai's surgery for congenital biliary atresia and underwent a living-related orthotopic LT. After LT, her allograft functioned well, but she continued to have hypoxemia and orthodeoxia. She was referred for rehabilitation for disuse atrophy, contracture of hip and shoulder joints, left common peroneal nerve palsy, and rehabilitation for respiratory dysfunction. By day 106 after LT, her orthodeoxia and disuse atrophy had improved because of daily exercise training and active joint range of motion exercises. Patients with HPS have orthodeoxia and poor responsiveness to oxygen therapy, and correction of hypoxemia after LT may be delayed. Therefore, rehabilitation approaches for patients with HPS should be based on the pathophysiology and characteristics of HPS.

Renal-protective effect of nondepressor dose of cicletanine in diabetic rats with hypertension

We assessed the renal and cardiac benefits of cicletanine (CIC), a furopyridine derivative drug with diuretic and antihypertensive properties, in diabetic spontaneously hypertensive rats with renal impairment. Uninephrectomized streptozotocin (STZ)-diabetic spontaneously hypertensive Izmo rats (SHRIzm) (10 weeks old) were randomly assigned to receive vehicle or CIC (100 mg/kg/day, orally), and age-matched, uninephrectomized STZ diabetic Wistar-Kyoto Izmo rats (WKYIzm) were assigned to receive vehicle for up to 12 weeks. Blood pressure increased progressively in diabetic SHRIzm but not in diabetic WKYIzm. Urinary albumin excretion increased significantly in both diabetic SHRIzm and diabetic WKYIzm throughout the experiment. The antihypertensive effect of CIC was not significantly observed in diabetic SHRIzm. However, the subdepressor doses of CIC significantly decreased urinary albumin excretion, serum creatinine, and blood urea nitrogen in diabetic SHRIzm. These results were confirmed by morphological analysis of kidneys in each group of rats. The index of focal glomerular sclerosis (FGS) in diabetic SHRIzm was significantly higher than that in diabetic WKYIzm. The CIC treatment significantly and effectively protected against an increase in the index of FGS in diabetic SHRIzm. Moreover, CIC treatment significantly attenuated the increase in the heart weight to body weight ratio in diabetic SHRIzm. Treatment with CIC did not affect urinary and blood glucose concentrations at this dose. These results suggest that CIC has a renal-protective action, which is not related to improvement of diabetes or improvement of high blood pressure in diabetic rats with hypertension. The action might be due to the reduction of intraglomerular capillary pressure or protection of the renal glomerular vascular endothelial cell injury and mesangial cell injury through stimulation of PGI2 generation or elimination of free radicals, although the mechanism remains to be further investigated.

Decreased binding sites of angiotensin II in rat LY-80 and AH109A tumour and human gastric cancer using quantitative in vitro autoradiography

BACKGROUND

Under systemic hypertension induced by angiotensin II (AII) infusion, an attenuated vasoconstrictive response to the infusion in tumours was observed and a marked increase in tumour blood flow was observed in comparison with that in normal tissues. The results show a parallel circuit that connects the vascular bed of the pre-existing tissue to that of the tumour. The phenomenon was absent when hypertension was provoked by other vasoconstrictive agents such as norepinephrine or endothelin-1. However, the biological basis for this attenuated vasoconstrictive response to angiotensin II observed in tumours has not been fully elucidated.

METHODS

We assessed this response to characterise the angiotensin II receptor density and affinity in normal and tumour tissues. AH109A and LY80 tumour cell lines were transplanted to the skin in nude rats. Four weeks later, the rats were sacrificed. 125I-[Sar1, Ile8] angiotensin II was used to map its receptors in rat tissues using in vitro computerised autoradiography. Operated human gastric cancer tissues from a 49-year-old and a 66-year-old male patients were also investigated.

RESULTS

The numbers of angiotensin II receptors were markedly reduced in tumour tissues without a change of affinity. The numbers in AII-R in tumours were shown to be mainly AT1 by the marked reduction in radioligand binding achieved by losartan but not by PD123177. The same results were observed in human gastric cancer.

CONCLUSIONS

These results suggest that the decrease in angiotensin II receptors in tumours may explain the haemodynamic effect of angiotensin II-induced hypertension on tumour blood flow. This condition for drug delivery to tumour tissue may play a major role in enhancing the therapeutic effects of chemotherapy.

[Evaluation of visceral impairments by exercise testing: practice and problems in recently-developed exercise testing in disabled patients and an introduction of a newly-developed instrument for monitoring cardiopulmonary and postural parameters]

OBJECTIVE

Exercise testing plays a major role in evaluation of visceral impairments in disabled patients. We introduced recently-developed exercise testing and a newly-developed instrument for monitoring cardiopulmonary and postural parameters. We also evaluated the effects of cardiac phase II rehabilitation, pulmonary rehabilitation, and lung volume reduction surgery (LVRS) in patients with cardiopulmonary diseases.

METHODS

1) The ratio of ischemic heart disease in stroke patients was assessed by exercise testing. 2) The physical status of the patients with myocardial infarction (MI) was assessed before and just after our hospitalized cardiac phase II rehabilitation program, and at a 6-month follow-up by cardiopulmonary exercise testing. 3) The physical status of the patient with idiopathic interstitial pneumonia was assessed before and after pulmonary rehabilitation by a six-minute walking test. 4) The physical status of the patients with pulmonary emphysema (PE) was assessed before and 3 months after LVRS. 5) We introduced a newly-developed instrument for monitoring cardiopulmonary and postural parameters (MCPP).

RESULTS AND CONCLUSIONS

The ratio of ischemic heart disease (IHD) in stroke patients was 18%. Our hospitalized phase II cardiac rehabilitation program improved the management of cardiac risk factors and the physical status in patients with MI. The physical status of the patient with idiopathic interstitial pneumonia was markedly improved after pulmonary rehabilitation, and she did not need to undergo lung transplantation. The physical status and lung function of PE was significantly improved 3 months after LVRS. MCPP was made and used in the field of rehabilitation medicine. MCPP shows the picture and cardiopulmonary and postural parameters at the same time on a monitor, and is a very useful tool to evaluate the activities of daily living of the patients undergoing rehabilitation. MCPP may provide useful information to develop more efficient strategies for rehabilitation planning and patients' education.

Physical and psychological improvements after phase II cardiac rehabilitation in patients with myocardial infarction

We have designed a new 4-week hospitalized phase II cardiac rehabilitation program. The purpose of the present study is to clarify whether the physical and psychological status of patients with myocardial infarction (MI) improves after participation in our program. Twenty-nine patients (27 males, two females) with acute MI who enrolled in the 4-week hospitalized phase II rehabilitation program were assessed. All patients enrolled in this study had received coronary interventions. The rehabilitation consisted of exercise training, education and counseling. We evaluated the physical and psychological status of the patients before and just after the program, and at a 6-month follow up. The physical status was assessed by exercise tolerance measured by the peak oxygen consumption and anaerobic threshold, frequency of exercise, and serum concentrations of triglyceride, total cholesterol, high-density lipoprotein-cholesterol, and low-density lipoprotein-cholesterol. The psychological status was assessed by the Spielberger state-trait anxiety inventory questionnaire (STAI) and the self-rating questionnaire for depression (SRQ-D). Thirty-four patients (27 men, seven women) with MI who did not participate in our rehabilitation program served as a control group. After participation in our rehabilitation program, exercise tolerance and the serum lipid profiles of the patients were improved compared with those before rehabilitation. These parameters had improved significantly 6 months after rehabilitation. The STAI anxiety score was improved significantly and the SRQ-D depression score tended to be improved just after the rehabilitation program. Regular physical activity was continued even 6 months after the completion of the program. Our hospitalized phase II cardiac rehabilitation program improved the management of cardiac risk factors and the psychological status in patients with MI. This comprehensive program may contribute to the secondary prevention of MI as well as the recovery of physical and psychological activities.

Renal-protective effect of non-depressor dose of cicletanine in streptozotocin diabetic rats

OBJECTIVE

To assess the renal benefits of cicletanine (CIC) in diabetic rats with renal impairment.

METHODS

Hemi-nephrectomized streptozotocin-diabetic Wistar-Kyoto Izmo rats (WKYIzm) (10 weeks old) were randomly assigned to receive vehicle or a low or high dose of CIC (30 or 100 mg/kg per day, orally) for 12 weeks.

RESULTS

The blood pressure was raised slightly but not significantly in this model. An anti-hypertensive effect of CIC was not significantly observed. However, the sub-depressor doses of CIC significantly and dose-dependently decreased urinary albumin excretion. These results were confirmed by morphological analysis of kidneys in each group of rats. CIC treatment significantly and effectively protected against an increase in the percentage of focal glomerular sclerosis. CIC did not affect urinary and blood glucose concentrations at either dose.

CONCLUSIONS

These results suggest that CIC has a renal-protective action, which is not related to improvement of diabetes or of high blood pressure in this model. The action might be due to the reduction of intraglomerular capillary pressure, although the mechanism remains to be further investigated.

[Effects of chronic exercise on renal function in 5/6 nephrectomized spontaneously hypertensive rats (SHR)]

We assessed the renal effects of chronic treadmill exercise in the remnant kidney model of chronic renal failure. Eight-week-old spontaneously hypertensive rats (SHR) were subjected to 5/6 nephrectomy by removal of the left kidney and infarction of two thirds of the right kidney. We performed two series of experiments. Firstly, we investigated the renal effects of chronic mild treadmill exercise in 5/6 nephrectomized SHR. The SHR were divided into 2 groups: a non-exercising group (Non-Ex) and a group conducting mild treadmill running at 20 m/min 0 degree grade for 30 min (Mild-Ex) 5 times/week for 4 weeks. Secondly, we investigated the effects of moderate or severe treadmill exercise in the rats. The SHR were divided into 3 groups: a non-exercising group (Non-Ex), a group conducting moderate treadmill running at 20 m/min 0 degree grade for 60 min (Moderate-Ex) and, a group conducting severe treadmill running at 35 m/min 0 degree grade for 60 min (Severe-Ex) 5 times/week for 4 weeks. Chronic treadmill exercise significantly attenuated the increase in proteinuria and serum total cholesterol levels intensity-dependently. These results were confirmed by morphological analysis of the kidneys. Moderate-Ex provided significantly effective protection against an increase in focal glomerular sclerosis. These results indicate that exercise did not worsen renal function and in contrast, suggest a renal-protective action in this rat model.

Relation between natriuresis and urinary excretion of hydrogen peroxide

Changes in the urinary hydrogen peroxide by exercise or salt load were studied in six healthy male volunteers. Exercise was performed by bicycle ergometer for 30 min at the intensity of 80% of the maximum heart rate predicted by age. Urinary excretion rate of hydrogen peroxide showed a tendency to increase in the salt load experiment, and to decrease by exercise. Correlation coefficient between urinary excretion rate of sodium and hydrogen peroxide one hour after the load was 0.797 (0.1 > p > 0.05) in the exercise experiment, 0.892 (p <0.05) in the salt load experiment and 0.877 (p < 0.001) in both experiments. Correlation coefficient between area under the curve for sodium excretion and hydrogen peroxide excretion was also as high as 0.822 (p < 0.05) in the exercise experiment, 0.909 (p < 0.05) in the salt load experiment and 0.853 (p < 0.001) in both experiments. These results may suggest that urinary excretion rate of hydrogen peroxide is closely related to metabolism of electrolytes and fluid in the renal tubules.

Muscle damage induced by experimental hypoglycemia

To determine organ damage due to hypoglycemia, we studied the effects of insulin dose and hypoglycemia duration on serum enzyme activity in rabbits. Thirty rabbits were randomly divided into five groups according to hypoglycemia duration and insulin dose: A2, hypoglycemia for 30 minutes with 2 U/kg insulin; A10, hypoglycemia for 30 minutes with 10 U/kg insulin; B2, hypoglycemia for 60 minutes with 2 U/kg insulin; B10, hypoglycemia for 60 minutes with 10 U/kg insulin; and C, no hypoglycemia with 10 U/kg insulin and 50% glucose. Insulin-induced hypoglycemia was reversed by intravenous injection of glucose. Alterations in serum enzyme activity and creatine kinase (CK) isoenzyme distribution were determined before and after insulin injection. Serum CK activity increased significantly in all hypoglycemic groups compared with preinjection values, and tended to remain high for 24 hours in both groups A10 and B10. Serum activity of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) increased only in group B10. In addition, the level of band 4 of serum CK isoenzymes, which exists predominantly in skeletal muscle and myocardium, increased significantly in group B10. These results suggest that the increase in both serum enzyme and CK band 4 isoenzyme activities during hypoglycemia is primarily due to damage in muscle rather than liver, and that the hypoglycemia duration and insulin dosage may influence the extent of organ damage.

Angiotensin-converting enzyme inhibition and salt in experimental myocardial infarction

It is well known that angiotensin-converting enzyme inhibitors attenuate progressive ventricular enlargement or hypertrophy after myocardial infarction and that cardiac angiotensin-converting enzyme activity is increased in the rat model of myocardial infarction. In this study, to determine whether the beneficial effects of angiotensin-converting enzyme inhibition on cardiac hypertrophy after myocardial infarction are due to a reduction in ventricular afterload or to inhibition of cardiac angiotensin-converting enzyme, we used sodium loading during angiotensin-converting enzyme inhibition. The rat model of myocardial infarction was treated with a vehicle, 1% saline, as drinking fluid, perindopril (2 mg/kg/day), or 1% saline as drinking fluid plus perindopril (2 mg/kg/day) for 6 weeks. Perindopril reduced blood pressure, prevented cardiac hypertrophy, and inhibited cardiac angiotensin-converting enzyme. The effects of perindopril on blood pressure and cardiac hypertrophy were abolished by sodium loading, which did not alter the degree of cardiac angiotensin-converting enzyme inhibition. Thus the actions of perindopril on cardiac hypertrophy depend more on blood pressure reduction than on cardiac angiotensin-converting enzyme inhibition in the rat model of myocardial infarction.

Chronic effects of FR139317 and enalapril on renal failure rats with moderate exercise

We assessed the renal effects of moderate treadmill exercise in the spontaneously hypertensive rats (SHR) remnant kidney model of chronic renal failure (CRF). The effects of chronic administration of a specific endothelin (ET) subtype A (ETA) receptor antagonist, FR139317 (32 mg/kg/day i.p.) and an angiotensin-converting enzyme inhibitor, enalapril (2 mg/kg/day i.p.), in combination with moderate exercise were also investigated. Eight-week-old SHR were subjected to 5/6 nephrectomy. One week after surgery the rats were divided into five groups: (a) no treadmill running; (b) moderate treadmill running, 20 m/min for 60 min (Ex) per day; (c) Ex plus FR139317; (d) Ex plus enalapril; and (e) m-Ex plus enalapril in combination with FR139317, for 4 weeks. In SHR-CRF, Ex significantly attenuated the increase in urinary protein excretion. Enalapril significantly attenuated the increase in systolic blood pressure and urinary protein excretion. FR139317 at this dose did not show any antihypertensive or renal protective effect in this model. These results suggest that moderate exercise may protect renal function in SHR CRF. They also suggest that FR139317 may not have an additional antihypertensive and renal protective effect in this exercise model.

Endothelin receptors and angiotensin II receptors in tumor tissue

In cancer chemotherapy, selective enhancement of drug delivery to tumor tissue is essentially important for increase of chemotherapeutic effects. An attenuated vasoconstrictive response to angiotensin II (Ang II) in tumors and a marked increase in tumor blood flow were observed compared with normal tissues during systemic hypertension induced by Ang II infusion. The phenomenon was absent when hypertension was provoked by endothelin-1 (ET-1). We assessed this response to characterize ET receptor and Ang II receptor density and affinity in normal and tumor tissues. The tumor cell line LY80 was transplanted to the skin in nude rats. Four weeks later the rats were sacrificed. [125I] ET-1 and [125I Sar1, Ile8]-Ang II were used to map the receptors for ET and Ang II in rat tissues using computerized in vitro autoradiography. A moderately high density of ET receptors, (ETB > ETA) was found in tumors. The Ang II receptors were markedly reduced in tumor tissues without changes in the affinity. These results suggest that the decrease in Ang II receptors but not ET receptors in tumors may explain the hemodynamic effect of Ang II-induced hypertension and ET-induced hypertension on tumor blood flow.

Further studies concerning possible transmitters from NANC nerves in the circular muscle of the rat stomach fundus

We examined the characteristics of the non-adrenergic, non-cholinergic (NANC) inhibitory response of the circular muscle of the rat stomach fundus to transmural nerve stimulation or high K+. Treatments with isotonic high K+ (20 mM), nitric oxide (NO) and sodium nitroprusside (SNP) all elevated cyclic GMP levels in the rat stomach fundus in the presence of atropine and guanethidine. Isotonic high K+-induced formation of cyclic GMP was completely inhibited by tetrodotoxin (TTX) or NG-nitro-L-arginine (L NNA). The K+ also increased cyclic AMP levels and this response was completely inhibited by TTX. Dose-dependent relaxation of the fundus in response to SNP was shifted to the right by a prior incubation with high concentration of SNP (10(-4) M) for 2 hrs. Incubating the fundus with SNP for 2 hrs significantly inhibited NO induced cyclic GMP formation. Relaxation responses to transmural stimulation (1 Hz or 30 Hz), isotonic high K+ and NO were significantly reduced by a prior incubation with SNP. Isotonic high K+ (20 mM)-induced relaxation of circular muscle strips was not completely inhibited by combined treatment with 10(-5)M L-NNA, 5 x 10(-5)M oxyhemoglobin and anti VIP (1:200). These results suggest that NO as well as VIP is possible transmitter from NANC nerves in the circular muscle of the rat stomach fundus and there should be one or more inhibitory mediators other than VIP and NO.

FMLP actions and its binding sites in isolated human coronary arteries

The chemoattractant f-Met-Leu-Phe (FMLP) can modulate human coronary arterial tone without the involvement of peripheral leukocytes. We investigated the actions of FMLP and its cellular mechanism in human coronary arteries isolated 2-3 h after death. A single dose of FMLP (0.01-10 microM) produced transient contraction (or, followed by relaxation) responses in most human coronary rings examined. These responses to FMLP were in large part mediated by the generation of cyclooxygenase products, mainly thromboxane A2 (TXA2) and prostaglandin I2 (PGI2). Radiolabeled N-formyl hexapeptide. 125I-f-Nle-Leu-Phe-Nle-Tyr-Lys bound densely to intimal and adventitial sites that accumulated macrophages (CD68-positive) with a Kd of 14-29 nM and, further, weakly to the media with a Kd of 2.4-3.6 microM. Several cell types including macrophages, endothelial cells and smooth muscle cells were positively immunostained for both TXA2 synthase and PGI2 synthase. However, there was no significant relation between the magnitude of the responses to FMLP and dense macrophage accumulation in the intimal plaques or the adventitia. A reverse transcription-polymerase chain reaction showed predominant expression of FMLP receptor homologues, FPRH1 and FPRH2 mRNA, in human coronary medial tissues relative to that in leukocytes. In conclusion. FMLP produced transient tension changes in human coronary arteries, mainly via the generation of TXA2 and PGI2. This effect of FMLP did not appear to be mediated by the activation of densely accumulated intimal and/or adventitial macrophages, but by the activation of unidentified medial tissue cells which might have functional FMLP receptor homologues.

Cardiac angiotensin converting enzyme and endothelin receptor in rats with chronic myocardial infarction

To ascertain the pathophysiological roles of the renin-angiotensin system and endothelin in heart failure and cardiac hypertrophy, we assessed changes in cardiac angiotensin converting enzyme (ACE) and endothelin-1 (ET-1) receptor using rats in which myocardial infarction was induced by left coronary ligation. The animals were decapitated 1 or 8 months after the operation. Cardiac ACE and ET-1 receptor were quantified by computerized in vitro autoradiography using 125I-MK351A (a lisinopril derivative) and 125I-ET-1. One month after myocardial infarction, cardiac weight and plasma atrial natriuretic peptide had increased in rats with infarction, compared to sham-operated controls, indicating the presence of chronic left ventricular dysfunction, although exchangeable body sodium and plasma renin activity were unchanged. Cardiac ACE increased markedly in the infarcted area and moderately in hypertrophied myocardium without any change in affinity compared to sham-operated rats. On the other hand, there was no change in cardiac ET-1 receptors in infarcted rats. The same results were found even at 8 months after myocardial infarction. The present study indicates that cardiac ACE may participate in tissue repair at the site of myocardial infarction and may also play a role in the pathophysiology of cardiac hypertrophy in rats with chronic heart failure. However, the present results do not reveal whether ET-1 receptor participates in the pathophysiology of cardiac hypertrophy in this model.

Plasma enzymic changes in insulin-induced hypoglycemia in experimental rabbits

In order to elucidate the effects of hypoglycemia on cardiac and skeletal muscle, plasma activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH) and creatine kinase (CK) were assessed in rabbits with hypoglycemia induced by i.v. injection of insulin. After hypoglycemia lasting for more than 30 min, the plasma levels of ALT, AST and LDH rose significantly in 4 out of 5 rabbits reaching a peak at 24 hr. The plasma activity of CK rose remarkably and reached a peak at 6 hr after insulin injection in all rabbits. These results suggest prolonged hypoglycemia may cause myocardial and/or skeletal muscle damage, which can be ascertained by measuring plasma activities of the related enzymes.

Relaxation response to the rat stomach fundus to methylene blue

When methylene blue (10(-4) M) was applied to the rat stomach fundus precontracted with 10(-6) M serotonin in the presence of 10(-6)M atropine and 10(-6) M guanethidine, slowly developing relaxation was induced. Methylene blue (10(-4) M) increased cyclic AMP but not cyclic GMP levels in the stomach fundus. These results suggest that methylene blue may relax the rat stomach fundus through cyclic AMP formation.

Effects of benidipine, a calcium antagonist, on urinary kallikrein excretion and renal impairment in experimental diabetes

OBJECTIVE

To assess the long-term effects of different antihypertensive agents on urinary protein excretion and kallikrein excretion in diabetic rats with renal impairment.

METHODS

Uninephrectomized streptozotocin diabetic Wistar-Kyoto rats were randomly assigned to receive vehicle, a calcium antagonist (benidipine) or an angiotensin converting enzyme inhibitor (captopril) for up to 12 weeks. Active kallikrein was determined by its kininogenase activity, and generated kinins were measured by radioimmunoassay. Total kallikrein was also determined by measuring kininogenase activity after inactive kallikrein had been activated with trypsin.

RESULTS

Urinary protein excretion increased significantly in diabetic rats compared with non-diabetic rats. Urinary active kallikrein excretion was significantly reduced in diabetic rats, whereas urinary total kallikrein excretion was unchanged, resulting in a reduced percentage of active to total kallikrein compared with that in non-diabetic rats. Benidipine and captopril reduced blood pressure and attenuated the development of diabetic renal impairment in a similar manner. However, only benidipine attenuated the decreases in urinary active kallikrein excretion and the ratio of active to total kallikrein in diabetic rats.

CONCLUSIONS

Although pathophysiological relevance of impaired urinary kallikrein activation to the development of diabetic renal impairment remains to be determined, our result might suggest a new mechanism by which calcium antagonists protect the kidney from diabetic renal impairment.

Cardiomegaly and vasoactive hormones in rats with chronic myocardial infarction: long-term effects of chlorothiazide

1. The effects of prolonged chlorothiazide treatment of left ventricular failure on cardiac hypertrophy, circulating vasoactive hormones and exchangeable body sodium were examined in rats with chronic myocardial infarction induced by left coronary artery ligation. Chlorothiazide therapy commenced either immediately or 2 weeks after infarction. For 4 weeks, the rats were given either chlorothiazide (50 mg day-1 kg-1) in their drinking water or drinking water alone. 2. Cardiac weight increased in untreated rats with infarction in comparison with sham-operated controls, indicating the presence of chronic left ventricular dysfunction, although exchangeable body sodium, plasma renin activity, plasma vasopressin and plasma osmolality remained unchanged. 3. Chlorothiazide raised haematocrit and plasma renin activity equally in rats with and without infarction, although exchangeable body sodium, plasma vasopressin and plasma osmolality were not changed by the treatment. Plasma atrial natriuretic peptide was 2-fold higher in rats with infarction and this response was not affected by chlorothiazide treatment. Chlorothiazide therapy did not prevent or reverse cardiac hypertrophy. 4. Chronic diuretic therapy in this experimental model of heart failure did not reduce extracellular sodium, plasma vasopressin or the extent of ventricular hypertrophy, possibly because the condition was associated with activation of the renin-angiotensin system.

Cardiovascular and renal protective effects of losartan in spontaneously hypertensive rats with diabetes mellitus

1. Cardiovascular and renal benefits of a specific angiotensin II (AII) receptor antagonist, losartan (LOS), were assessed in diabetic rats with renal impairment. 2. Uninephrectomized SHR made diabetic by streptozotocin administration were given LOS (5 mg/kg per day, i.p.) alone, captopril (CAP) (50 mg/kg per day, i.p.) alone, or a combination of CAP and LOS via osmotic minipumps for 8 weeks. 3. Both CAP alone and LOS alone completely blocked the development of hypertension in diabetic SHR in the same manner. CAP + LOS did not enhance the antihypertensive effects of LOS alone or CAP alone. 4. CAP + LOS, LOS alone and CAP alone significantly decreased urinary protein excretion and serum creatinine to the same extent. 5. These results indicate that both LOS and CAP exert antihypertensive and renoprotective effects in this model: these actions are mainly through inhibition of AII production.

Kinin and angiotensin II receptor antagonists in rats with chronic renal failure: chronic effects on cardio- and renoprotection of angiotensin converting enzyme inhibitors

OBJECTIVE

To assess the potential of the kallikrein-kinin and renin-angiotensin systems in mediating the cardio- and renoprotective effects of angiotensin converting enzyme (ACE) inhibitors in rats with chronic renal failure.

MATERIALS AND METHODS

Spontaneously hypertensive rats (SHR) and normotensive control Wistar-Kyoto (WKY) rats subjected to five-sixths nephrectomy were randomly assigned to treatment with vehicle, a kinin antagonist (Hoe 140) or an ACE inhibitor (cilazapril) or both drugs, intraperitoneally via osmotic minipumps for 4 weeks. In addition, the effects of a chronic infusion of a specific angiotensin receptor antagonist (losartan) alone or in combination with an ACE inhibitor (enalapril) were also investigated in nephrectomized SHR for 2 weeks.

RESULTS

In nephrectomized SHR and WKY rats, cilazapril alone significantly reduced systolic blood pressure, urinary protein excretion, heart weight and serum creatinine. In nephrectomized SHR, Hoe 140 alone or cilazapril in combination with Hoe 140 (7 or 70 mu g/kg per day) induced no changes in these parameters, other than those associated with the effects of cilazapril alone. In nephrectomized WKY rats, cilazapril in combination with Hoe 140 (70 mu g/kg per day) slightly, but not significantly, attenuated the antihypertensive effect of cilazapril but did not affect the other parameters. These results were confirmed by morphological analysis of kidneys. All the drug regimens provided effective protection against an increase in focal glomerular sclerosis. Enalapril did not modify the antihypertensive and renoprotective effects of losartan in nephrectomized SHR.

CONCLUSIONS

The present results indicate that the kallikrein-kinin system might not be a major factor in the cardio- and renoprotective effects of ACE inhibitors in rats with chronic renal failure.

Do kinins mediate cardioprotective and renoprotective effects of cilazapril in spontaneously hypertensive rats with renal ablation?

1. We assessed the potential of the kallikrein-kinin system in mediating the cardioprotective and renoprotective effects of an angiotensin-converting enzyme inhibitor (ACEI), cilazapril (CIL) in rats with renal ablation. 2. Eight week old spontaneously hypertensive rats (SHR) were subjected to 5/6 nephrectomy. One week after the operation, the rats were divided into 5 groups: (i) vehicle; (ii) CIL 1 mg/kg per day per os (p.o.); (iii) Hoe140 (HOE) 70 mu g/kg per day given intraperitoneally (i.p.); (iv) CIL 1 mg/kg per day p.o. plus HOE 7 mu g/kg per day i.p.; (v) CIL 1 mg/kg per day p.o. plus HOE 70 mu g/kg per day i.p. The treatment lasted for 4 weeks. 3. CIL alone significantly reduced systolic blood pressure, urinary protein excretion, heart weight and serum creatinine level. HOE alone did not induce any significant changes in these parameters. CIL in combination with HOE (7 or 70 mu g/kg per day) did not induce any changes in these parameters, in addition to those associated with the effects of CIL alone. 4. These results indicate that the kallikrein-kinin system might not play a major role in the cardioprotective and renoprotective effects of ACE inhibitors in the rat remnant kidney model of chronic renal failure.

Effects of recombinant human erythropoietin on blood pressure and renal function in SHR with chronic renal failure

1. The effects of chronic administration of erythropoietin (EPO) on blood pressure and renal function in rats with ablation of renal mass were assessed. 2. Spontaneously hypertensive rat were subjected to 5/6 nephrectomy (5/6Nx). Four weeks after the operation, the rats were randomly allocated to vehicle, EPO 20IU/kg i.p., or EPO 100 IU/kg i.p. (both given twice a week) for 4 weeks. 3. Marked anaemia was noted in SHR-5/6Nx. EPO caused a significant increase in haematocrit at a high dose but not at a low dose. A dose dependent relationship was noted in the EPO-induced rise in the systolic blood pressure. 4. EPO dose-dependently increased urinary protein excretion. It also increased blood urea nitrogen and serum creatinine levels. 5. These results suggest that EPO ameliorates anaemia and severely accelerates renal failure in SHR-5/6Nx. They also suggest that anaemia can be a haemodynamically favorable adaptation to chronic renal disease and that its correction may have adverse renal haemodynamic and structural consequences.

Antihypertensive and renal-protective effects of losartan in streptozotocin diabetic rats

OBJECTIVE

To assess the renal benefits of a specific angiotensin II receptor antagonist, losartan, in diabetic rats with renal impairment.

DESIGN AND METHODS

Uninephrectomized streptozotocin diabetic spontaneously hypertensive rats (SHR) were randomly assigned to receive vehicle, or to receive losartan or captopril, or both, intraperitoneally via osmotic minipumps for 8 weeks.

RESULTS

Blood pressure and urinary protein excretion in the diabetic SHR increased progressively during the experimental period. Both captopril treatment and losartan treatment completely blocked the development of hypertension in diabetic SHR. Simultaneous administration of captopril and losartan did not enhance the antihypertensive effects of losartan treatment or captopril treatment. Furthermore, losartan treatment, captopril treatment and losartan + captopril treatment all significantly decreased urinary protein excretion, urinary albumin excretion and serum creatinine to the same extent. These effects were sustained for the entire experimental period and were not associated with any significant changes in body weight, urine volume, urine sugar and urinary electrolytes excretion. These results were confirmed by morphological analysis of kidneys in each group of rats. Losartan treatment, captopril treatment and losartan+captopril treatment all significantly and effectively protected against an increase in the percentage of focal glomerular sclerosis. Losartan treatment and captopril treatment both significantly attenuated the increase in heart weight: body weight ratio. The heart weight: body weight ratio in the losartan-treated group was significantly lower than in the captopril-treated group.

CONCLUSIONS

These results indicate that hypertension could accelerate diabetic renal impairment and that losartan has antihypertensive and renoprotective effects in this rat model. They also suggest that the antihypertensive and renoprotective effects of captopril treatment in this rat model are caused mainly by inhibition of angiotensin II production rather than stimulation of the kallikrein-kinin system or of vasodilator prostaglandins. The difference in potency between losartan treatment and captopril treatment to attenuate the increase in heart weight: body weight ratio might partly explain the existence in the heart of angiotensin-forming pathways, which are not dependent on angiotensin converting enzyme.

[Activity and localization of neutral metalloendopeptidase (EC 3.4.24.11) (NEP), the degradative enzyme for atrial natriuretic peptide (ANP), in rat kidney]

Atrial natriuretic peptide (ANP) is degraded by neutral metalloendopeptidase (EC 3.4.24.11) (NEP), and the kidney is the major site of ANP clearance. The regional distribution of NEP in rat kidney was investigated by an enzymatic method and by in vitro autoradiography. The activity of NEP, measured with an enzymatic fluorimetric method employing N-dansy 1-D-alanyl-glycy 1-L-4-nitrophenylalany 1-glycine as a synthetic substrate, was 18 times higher in the outer stripe and 8 times higher in the inner cortex than in the outer cortex. Low concentrations of NEP were found in the outer cortex, in the inner stripe and in the inner medulla. NEP activity in rat kidney was inhibited by specific NEP inhibitors (phosphoramidon, thiorphan, SCH39370, SCH47896 and SCH48446) at micromolar concentrations. SCH47896 is a phenolic derivative of SCH39370 which can be radioiodinated with 125I. SCH48446 is a di-iodo analog of SCH47896. Thus, [125I]SCH47896 retains the full enzymatic inhibitory activity and full biological potency to bind to the active site of NEP. Autoradiographs using [125I]SCH47896 demonstrated maximal bind to regions of the outer stripe of the outer medulla and to the inner cortex, which was consistent with binding to the deep proximal tubules. These bindings were displaced in a dose-dependent manner by NEP inhibitors. Enalaprilat did not displace [125I]SCH47896 binding. EDTA inhibited these bindings by 90%. The present result suggests that degradation of ANP by NEP occurs mainly in the deep proximal tubules, and that the proximal convoluted tubule in the outer cortex is not a major site of location of NEP.(ABSTRACT TRUNCATED AT 250 WORDS)

Involvement of nitric oxide pathway in non-adrenergic non-cholinergic (NANC) relaxation in the rat stomach: differential innervation of NANC nerves in the longitudinal and circular muscle of the fundus

1. The effects of NG-nitro-L-arginine (L-NNA) on non-adrenergic, non-cholinergic (NANC) relaxation elicited by transmural nerve stimulation (TNS) or high K+ were studied in the rat stomach fundus in order to investigate the mode of innervation of NANC nerves in the longitudinal and the circular muscle of the fundus. 2. Relaxation responses of the fundus to TNS were larger in circular than in longitudinal muscle strips. 3. Treatment with L-NNA (10(-5) M) reduced slightly but significantly the relaxation induced by TNS in both circular and longitudinal muscle strips of the fundus. The inhibitions of the TNS-induced relaxation by L-NNA were reversed partly by L-arginine (10(-3) M). 4. Although K+ produced concentration-dependent contraction in longitudinal muscle strips of the fundus, low concentration of K+ (20 mM) produced rapid and long-lasting relaxation in circular muscle strips of the fundus. 5. The 20 mM of K(+)-induced relaxation in circular muscle strips was significantly inhibited by L-NNA (10(-5) M) or oxyhemoglobin (2 x 10(-5) M). The inhibition of the K+ (20 mM)-induced relaxation by L-NNA was reversed by L-arginine (10(-3) M). 6. These results suggest that NO is one of mediators or transmitters in the NANC relaxation of the rat fundus, and that the density of NO-containing NANC nerves in the stomach fundus is richer in circular than in longitudinal muscle.

Urinary active kallikrein excretion and diabetic renal impairments in streptozotocin-treated rats

To assess possible roles of the renal kallikrein-kinin system in the development of renal impairments in diabetes mellitus, we determined daily excretion of urinary total and active kallikrein in uninephrectomized Wistar-Kyoto rats made diabetic by streptozotocin (45 mg/kg) as a bolus injection. We also evaluated the effect of captopril (50 mg/kg/day) administered orally on the development of diabetic renal impairments in the streptozotocin-treated rats. Active kallikrein was determined by its kininogenase activity, and generated kinins were radioimmunologically measured. Total kallikrein was also determined by measuring kininogenase activity after inactive kallikrein had been activated with trypsin (200 micrograms/ml). Urinary active kallikrein excretion was significantly reduced in streptozotocin-treated rats whereas urinary total kallikrein excretion was unchanged, resulting in the decreased ratio of active to total kallikrein compared to that in the controls. These reductions were preceded by the increased excretion of urine protein measured as an index of renal impairments. The administration of captopril for 12 weeks attenuated the development of diabetic renal impairments evaluated by urine protein excretion in streptozotocin-treated rats, although it did not induce significant changes in urinary total and active kallikrein excretion, and the ratio of active to total kallikrein. Thus the results of this study indicate that the renal kallikrein-kinin system might not play major roles in the development of diabetic renal impairments in the rat, although the pathophysiological relevance of impaired activation of renal kallikrein system to the development of diabetic renal impairments remains to be determined. In addition, they suggest that the renoprotective effects of captopril may be independent of the activation of renal kallikrein system in streptozotocin-treated rats.

The augmented blood pressure response to chronic angiotensin II infusion in partially nephrectomized rats

To assess potential roles of circulating levels of angiotensin II (Ang II) in the regulation of blood pressure in rats with reduced functional renal mass, we studied the blood pressure response to chronic infusion of Ang II at a subpressor dose in partially nephrectomized rats. Male Sprague-Dawley rats were subjected to 1/6, 2/6, 3/6, 4/6 and 5/6 nephrectomy, and sham operation a week before the infusion of Ang II at a rate of 400 micrograms/kg/day delivered intraperitoneally by osmotic minipumps for 14 days, or vehicle alone served as controls. Infusion of Ang II was associated with a slight but significant increase in systolic blood pressure in 1/6 nephrectomized rats (p < 0.05), whereas it did not induce a significant change in systolic blood pressure in sham-operated rats. Hypertension during Ang II infusion was more prominent in 2/6 nephrectomized rats than that in 1/6 nephrectomized rats (p < 0.05). However, there was no significant difference in hypertension during Ang II infusion among groups in 2/6, 3/6, 4/6 and 5/6 nephrectomized rats. Blood urea nitrogen and serum creatinine levels, endogenous creatinine clearance, urinary excretion of protein as indices of renal function, and urinary sodium excretion were not affected by chronic infusion of Ang II in 1/6, 2/6, 3/6, 4/6 and 5/6 nephrectomized, and sham-operated rats. There was also no significant difference in circulating levels of Ang II among Ang II infused-groups in 1/6 and 2/6 nephrectomized rats. These results indicate that elevated levels of circulating Ang II are capable of causing a sustained hypertension in rats with reduced functional renal mass.(ABSTRACT TRUNCATED AT 250 WORDS)

Chronic treatment with anti-endothelin antibodies fails to modify the development of hypertension in stroke-prone spontaneously hypertensive rats and DOCA-salt hypertensive rats

This study was designed to assess whether blocking endogenous endothelin with anti-endothelin antibodies could alter the development of hypertension in stroke-prone spontaneously hypertensive rats (SHR) and DOCA-salt treated rats. Specific anti-endothelin antibodies were produced in rabbits by standard methods. The amount of anti-endothelin antibodies employed in this study blocked the hypertensive effect of endothelin-1, 750 ng/kg, by 55% in conscious rats. Intravenous injection of anti-endothelin antibodies as a bolus twice a week for 3 weeks did not affect the rise in blood pressure of stroke-prone SHR (268 +/- 8 mmHg, n = 8) compared to control stroke-prone SHR (256 +/- 7 mmHg, n = 8) treated with normal rabbit serum. Intravenous administration of anti-endothelin antibodies in a same manner also failed to alter the development of hypertension in DOCA-salt treated rats (160 +/- 6 mmHg in anti-endothelin antibodies-treated group, n = 7 compared to 164 +/- 5 mmHg in normal rabbit serum-treated group, n = 7). The administration of anti-endothelin antibodies did not induce any significant changes in body weight, urine volume and urinary sodium excretion in stroke-prone SHR and DOCA-salt treated rats compared to those treated with normal rabbit serum. These findings suggest that circulating endothelin might not play a major role in the regulation of blood pressure in stroke-prone SHR and DOCA-salt treated rats.

Endothelin-1 augments pressor response to angiotensin II infusion in rats

To assess possible roles of endothelin in the regulation of blood pressure, we studied effects of a subpressor dose of endothelin-1 (3 micrograms/kg/day) on chronic blood pressure responses to infusion of angiotensin II and norepinephrine in rats. Rats were infused with angiotensin II at a subpressor dose (400 micrograms/kg/day i.p.) or with norepinephrine at a subpressor dose (360 micrograms/kg/day i.p.) for 6 days. Systolic blood pressure was significantly elevated during combined infusion of endothelin-1 and angiotensin II, whereas endothelin-1 alone or angiotensin II alone failed to induce any significant changes in systolic blood pressure compared with vehicle alone. This effect was sustained for the whole experimental period and was not associated with any significant changes in body weight, fluid intake, urine volume, or urinary electrolyte excretion. In contrast, combined infusion of endothelin-1 and norepinephrine failed to elevate systolic blood pressure, and no significant difference in systolic blood pressure was observed for the whole experimental period among the four groups of rats with endothelin-1 in combination with norepinephrine, endothelin-1 alone, norepinephrine alone, and vehicle alone. The present results indicate that angiotensin II and endothelin-1, but not norepinephrine and endothelin-1, work synergistically to raise the blood pressure and also suggest the possibility that endothelin-1 may modulate blood pressure control.

[The treatment of hypertensive patients with renal insufficiency--a comparison of the blood pressure management in patients with diabetic nephropathy and patients with hypertensive nephropathy]

It is well known that hypertension (HT) is frequently accompanied with diabetic nephropathy (DN) and that HT contributes to progression of DN. Thus, proper anti-hypertensive therapy is required in hypertensive patients with DN. However, there is so far no consensus of optimal blood pressure (BP) level to maintain the renal function in these patients. In order to evaluate the optimal BP level in the patients with renal insufficiency, we investigated the relation between BP and renal function in 15 DN patients with HT (aged 56.9 +/- 11.7 years at the first medical examination; 6 male and 9 female, total 117 patient-years) and 20 patients with hypertensive nephropathy (aged 44.3 +/- 13.0 years at the first medical examination; 17 male and 3 female, total 207.5 patient-years) as the control, who receive antihypertensive therapy for more than 4 years as outpatients at the second department of internal medicine of Tohoku University Hospital between 1974 and 1990. During this period 7 patients with DN came to receive hemodialysis therapy 2 to 6 (average 3.8 +/- 1.3) years after the first medical examination. As a result, in patients with hypertensive nephropathy, there was a tendency to show that the lower the mean BP was, the better the renal function. On the contrary, in DN patients there was an optimal mean BP (MBP) range; i.e, when MBP was controlled in this range, the deterioration rate of renal function was delayed, while deviation of MBP from this range made the renal function worse (p less than 0.01). However, this range varied with the serum creatinine (SCr) concentration level.(ABSTRACT TRUNCATED AT 250 WORDS)

[Comparison between endothelin binding sites and sarafotoxin S6B binding sites in rat tissues: studies by quantitative in vitro receptor autoradiography]

Sarafotoxin S6B(SRT), a peptide in snake venom, has a high degree of sequence homology with endothelin (ET) and both are potent vasoconstrictors. In order to determine whether SRT acts via the ET receptor, we performed autoradiographic binding studies on rat tissues using the radioligands, 125I-ET-1 and 125I-SRT and computerized in vitro autoradiography. In the heart, a high density of ET binding was found in the atria, and moderate density was found in the ventricles. A high density of ET-1 was found in the heart. In the kidney, ET-1 binding occurred in association with glomeruli, outer cortex, and inner stripe and inner medulla. In the adrenal, a high density of ET-1 binding occurred in the medulla as well as the zona glomerulosa. The binding affinity constant (KA) for ET-1 binding in these sites ranged from 1-10 x 10(9) M-1. Although SRT was 5-100 fold weaker than ET-1 in displacing 125I-ET-1 from these sites, 1 microM unlabelled SRT completely abolished 125I-ET-1 binding in all sites. Other venom peptides or unrelated peptides did not affect 125I-ET-1 binding. Moreover, the pattern of 125I-SRT binding in rat tissues by in vitro autoradiography was identical with that of 125I-ET-1 binding, and both unlabelled SRT and unlabelled ET-1 fully competed with 125I-SRT for binding. These results provide evidence that SRT binds to the ET binding sites in a range of rat tissues.

In vitro autoradiographic endothelin-1 binding sites and sarafotoxin S6B binding sites in rat tissues

1. The distribution of binding sites for [125I]-labelled endothelin-1 ([125I]-ET-1) and [125I]-labelled sarafotoxin S6B ([125I]-SRT) was visualized in rat tissues using in vitro autoradiography. 2. A high density of endothelin-1 (ET-1) binding was found in the heart. In the kidney, ET-1 binding occurred in association with glomeruli, proximal tubules, the inner stripe and inner medulla. In the adrenal, a high density of ET-1 binding occurred in the medulla as well as the zona glomerulosa. 3. The binding affinity constant (KA) for ET-1 binding in these sites ranged from 1 to 10 x 10(9)/mol per litre. 4. Although sarafotoxin S6B (SRT) was 10-100-fold weaker than ET-1 in displacing [125I]-ET-1 from these sites, 1 mumol/L unlabelled SRT completely abolished [125I]-ET-1 binding in all sites. Other venom peptides did not affect [125I]-ET-1 binding. 5. The pattern of [125I]-SRT receptor binding in rat tissues by in vitro autoradiography was identical to that for ET-1 receptor binding, and both unlabelled SRT and unlabelled ET-1 fully competed with [125I]-SRT for binding. 6. These results provide evidence that SRT binds to the ET receptor in a range of rat tissues. The results suggest that there may be subclasses of ET receptors which can be distinguished by the relative potencies of ET-1 and SRT at various tissues.