Case Report: QT Prolongation and Abortive Sudden Death Observed in an 85-Year-Old Female Patient With Advanced Lung Cancer Treated With Tyrosine Kinase Inhibitor Osimertinib

Cardiac arrest occurred in an 85-year-old female administered osimertinib for advanced lung cancer expressing epidermal growth factor receptor (EGFR) mutations. Electrocardiogram (ECG) recorded at recurrence of spontaneous circulation showed sinus rhythm associated with mild QT prolongation (QTc = 455 ms) to which silent myocardial ischemia and coadministration of itraconazole and herbal drug causing hypokalemia (2.1 mEq/L) may have contributed. Discontinuation of osimertinib, itraconazole and herbal drug, potassium supplementation and percutaneous coronary intervention alleviated QT prolongation (QTc = 432 ms). Osimertinib is the third-generation tyrosine kinase inhibitor lengthening QT interval, and careful monitoring of ECG, serum potassium and drugs coadministered during chemotherapy including osimertinib are highly required.

Association of systolic blood pressure and pulse pressure with carotid intima thickness in elderly Japanese patients

Many studies have demonstrated that increased carotid intima-media thickness (IMT) is related to future cardiovascular events and is influenced by cardiovascular risk factors such as sex, hypertension, diabetes, and hypercholesterolemia. Although aging is a well-known risk factor for an increase in carotid IMT, few studies have investigated which factors influence carotid IMT in the very elderly. In the present study, we investigated the relationship of pulse pressure (PP), blood pressure (BP), and its variability (six consecutive visits) with carotid IMT among 240 high-risk elderly in whom risk factors were managed clinically (average age was 79 ± 5 years). In the simple correlation, mean systolic BP (SBP) had a positive correlation with IMT and max IMT (P = .012 and P = .045), as did PP (P = .018 and P = .004), but did not diastolic BP or standard deviation of BP and coefficient of variation of BP. In multiple regression analyses, mean SBP and mean PP were each determinants of both IMT and max IMT, when each parameter was added separately to the regression model. We concluded that high SBP and wide PP still have an influence on increased carotid IMT in the very elderly Japanese patients.

Does decreased diastolic blood pressure associate with increased mortality in 80-year-old Japanese?

Hypertension is one of the greatest risk factors for cardiovascular disease, but its contribution to cardiovascular mortality weakens with aging. We have previously demonstrated that at the age of 80, higher systolic blood pressure (SBP) is not correlated with increased mortality in Japan. However, we did not examine in detail whether diastolic blood pressure (DBP) independently affects mortality. In the present study, 639 participants, who were 80 years old in 1997, were enrolled. The subjects were divided by their DBP [below 70 mmHg (group 1, n = 136), from 70 mmHg to 80 mmHg (group 2, n = 200), from 80 mmHg to 90 mmHg (group 3, n = 194), over 90 mmHg (group 4, n = 109)]. During the 4-year follow-up period, 90 individuals died. Cox multivariate regression analysis revealed that group 1 showed a significantly higher mortality rate than group 4 [relative risk (RR) 2.47, confidence interval (CI) 1.07-5.70, p = 0.03)]. The relative risks of deaths from cardiovascular diseases, pneumonia, and cancer tended to be higher in group 1 than in group 4, but the difference did not reach statistical significance. These results suggest that decreased DBP is associated with higher mortality in the Japanese elderly.

Serum albumin levels as an independent predictor of 4-year mortality in a community-dwelling 80-year-old population

BACKGROUND AND AIMS

Although serum albumin levels are associated with mortality in non-institutionalized elderly people under 80 years old, as well as in the institutionalized very elderly, little is known about the relationship in community-dwelling very elderly people. We, therefore, examined the association in a Japanese population of 80-year-old community residents.

METHODS

Serum albumin levels were measured in 672 (267 men, 405 women) out of 1282 80-year-old individuals. Over the following 4 years, the dates and causes of death were recorded from resident registration cards and official death certificates.

RESULTS

Of the above individuals, 107 subjects died (58 men, 49 women: 27 due to cancer, 27 cardiovascular disease, and 22 pneumonia). Survival rates were compared among 4 groups (highest >or=45 g/L, higher than 43-44 g/L, lower than 41-42 g/L, lowest <or=40 g/L). After adjustment for confounding factors, total death or cardiovascular death in the lowest albumin group was 3.1 times and 10.7 times more incident than in the highest albumin group, but there were no differences among groups as regards deaths due to cancer or pneumonia.

CONCLUSION

Serum albumin levels are an independent predictor of mortality due to all-cause or cardiovascular disease, but not of mortality due to cancer or pneumonia in very elderly Japanese community residents.

Correlation between increased urinary sodium excretion and decreased left ventricular diastolic function in patients with type 2 diabetes mellitus

BACKGROUND

Increased salt intake may induce hypertension, lead to cardiac hypertrophy, and exacerbate heart failure. When elderly patients develop heart failure, diastolic dysfunction is often observed, although the ejection fraction has decreased. Diabetes mellitus (DM) is an established risk factor for heart failure. However, little is known about the relationship between cardiac function and urinary sodium excretion (U-Na) in patients with DM.

METHODS

We measured 24-hour U-Na; cardiac function was evaluated directly during coronary catheterization in type 2 DM (n = 46) or non-DM (n = 55) patients with preserved cardiac systolic function (ejection fraction > or = 60%). Cardiac diastolic and systolic function was evaluated as - dp/dt and + dp/dt, respectively.

RESULTS

The average of U-Na was 166.6 +/- 61.2 mEq/24 hour (mean +/- SD). In all patients, stepwise multivariate regression analysis revealed that - dp/dt had a negative correlation with serum B-type natriuretic peptide (BNP; beta = - 0.23, P = .021) and U-Na (beta = - 0.24, P = .013). On the other hand, + dp/dt negatively correlated with BNP (beta = - 0.30, P < .001), but did not relate to U-Na. In the DM-patients, stepwise multivariate regression analysis showed that - dp/dt still had a negative correlation with U-Na (beta = - 0.33, P = .025).

CONCLUSION

The results indicated that increased urinary sodium excretion is associated with an impairment of cardiac diastolic function, especially in patients with DM, suggesting that a reduction of salt intake may improve cardiac diastolic function.

Role of Rho kinase and oxidative stress in cardiac fibrosis induced by aldosterone and salt in angiotensin type 1a receptor knockout mice

Large clinical trials have shown that mineralocorticoid receptor (MR) antagonists improve cardiovascular or total mortality in patients with heart failure or myocardial infarction even though the patients were taking angiotensin-converting enzyme inhibitors or angiotensin II receptor (AT1R) antagonists. We previously reported that cardiac fibrosis induced by aldosterone and salt (Ald-NaCl) was exaggerated in AT1aR knockout mice (AT1aR-KOs). As the association of Rho kinase and oxidative stress was reported in Ald-NaCl-induced hypertension of rats, we investigated the effects of an MR antagonist (eplerenone) and a Rho kinase inhibitor (fasudil) on Ald-NaCl-induced cardiac fibrosis in AT1aR-KOs. AT1aR-KOs were administered aldosterone (0.15 microg/h) subcutaneously using an osmotic minipump and were provided with 1% NaCl drinking water for 4weeks. AT1aR-KOs receiving Ald-NaCl were treated with a low (30 mg/kg/day) or high (100mg/kg/day) dose of eplerenone or a fasudil (100mg/kg/day). Systolic blood pressure (SBP), left ventricular weight/body weight (LVW/BW), histological examination and cardiac gene expression were evaluated on day 28. Ald-NaCl treatment caused increases in SBP and LVW/BW in AT1aR-KOs, and eplerenone dose-dependently decreased SBP, LVW/BW and cardiac fibrosis. Fasudil decreased LVW/BW and cardiac fibrosis without affecting SBP. The expressions of connecting tissue growth factor (CTGF) and nicotinamide adenine dinucleotide phosphate (NADPH) components (p22phox, p47phox and p67phox) were increased in Ald-NaCl-treated AT1aR-KOs, and eplerenone or fasudil decreased the expression of CTGF and NADPH components. Phosphorylated ERM (a marker of the phosphorylation of Rho kinase) was increased in Ald-NaCl-treated AT1aR-KOs and was decreased by eplerenone. Nitrotyrosine and 4-hydroxy-2-nonenal, which indicate tissue damage via oxidative stress, were increased in AT1aR-KO and were apparently attenuated by eplerenone or fasudil. These results suggested that the Rho kinase pathway was activated to induce cardiac fibrosis by Ald-NaCl via MR in AT1aR-KOs. A Rho kinase inhibitor as well as eplerenone might be useful for cardiac damage by Ald-NaCl.

Possible association of atrophic gastritis and arterial stiffness in healthy middle-aged Japanese

AIM

Helicobacter pylori (HP) has been implicated as a risk factor for cardiovascular and atherosclerotic diseases. Arterial stiffness determined by pulse wave velocity (PWV) or the cardio-ankle vascular index (CAVI) has been shown to be higher in HP-positive subjects than in HP-negative subjects; however, this result has been observed only in young subjects. The aim of the study was to investigate the possible correlation between HP infection and PWV or CAVI in middle-aged subjects.

METHODS

We measured brachial-ankle PWV (baPWV), CAVI, metabolism markers, pepsinogens (PGs) and IgG antibody to HP in 343 individuals aged either 60 or 65 year old. Atrophic gastritis (AG) was diagnosed based on the values of PGs.

RESULTS

baPWV and CAVI were significantly higher in the AG-positive group than in the AG-negative group even after adjusting for possible confounding factors (baPWVc; 16.63+/-3.50 vs. 15.59+/-3.47 p=0.010, CAVIc; 8.59+/-1.20 vs. 8.27+/-1.19 p=0.022). baPWV and CAVI values tended to be higher in the HP-positive group than in the HP-negative group. High-density lipoprotein (HDL) cholesterol level and the adiponectin level were lower in the AG-positive group than in the AG-negative group.

CONCLUSION

There may be an association between atrophic gastritis and atherosclerosis in middle-aged subjects.

Association between blood pressure and mortality in 80-year-old subjects from a population-based prospective study in Japan

Hypertension is one of the greatest risk factors for cardiovascular disease, but the contribution of high blood pressure to cardiovascular morbidity and mortality is weakened with aging. In the present study, we examined whether high blood pressure would be a risk factor for total and cardiovascular mortality in a group of very elderly Japanese. Six hundred and thirty-nine participants who were 80 years old in 1997 were enrolled. The subjects were divided into three groups on the basis of their systolic blood pressure (SBP) (below 140 mmHg [group 1, n=212], from 140 mmHg to 159 mmHg [group 2, n=217], over 160 mmHg [group 3, n=210]). During the 4-year follow-up period, 87 individuals died and 24 of these deaths were due to cardiovascular diseases. Cox multivariate regression analysis revealed that there was no association between total mortality and SBP levels (relative risk [RR] 1.71; confidence interval [CI] 0.81-3.58; group 3 compared with group 1, p=0.35). However, the subjects taking antihypertensive medication showed significantly higher mortality with increasing SBP level (RR 5.72, CI 1.03-31.6, p=0.04, group 3 compared with group 1). Furthermore, in the subjects with a cardiovascular disease such as angina or stroke, high SBP increased the total mortality (RR 13.4, CI 2.39-75.1, p=0.004, group 3 compared with group 1). The present study did not find an association between blood pressure and mortality in the very elderly. However, our results did suggest that high SBP increases the risk of mortality in patients with cardiovascular diseases and/or taking antihypertensive medication.

Aldosterone-and-salt-induced cardiac fibrosis is independent from angiotensin II type 1a receptor signaling in mice

Aldosterone infusion with high salt treatment induces cardiac fibrosis in rats. Aldosterone enhanced angiotensin II (Ang II) has been shown to induce proliferation and increase the expression of Ang II receptor mRNA and Ang II binding in vitro. To investigate the role of Ang II type 1a receptor (AT1aR) in aldosterone-and-salt (Ald-NaCl)-induced cardiac fibrosis, we subcutaneously infused aldosterone (0.15 microg/h) and 1% NaCl (Ald-NaCl) into AT1aR knockout mice (AT1aR-KO) or wild type mice (Wt). To examine the role of NaCl on cardiac fibrosis, we gave some of the aldosterone-treated AT1aR-KO tap water (Ald-H2O). Ald-NaCl treatment increased systolic blood pressure and induced cardiac hypertrophy in both strains, whereas there were no such changes in the mice without aldosterone. Severe cardiac fibrosis was seen in Ald-NaCl-treated AT1aR-KO and not in Ald-NaCl-treated Wt. In contrast, Ald-NaCl-treated Wt with co-administration of an active metabolite of olmesartan, the AT1aR antagonist (10 mg/kg/day) did not show cardiac fibrosis. Na+/H+ exchanger, and Na+-K+ ATPase alpha2 subunit mRNA were decreased in AT1aR-KO. Na+/Ca2) exchanger mRNA was lower in AT1aR-KO than Wt and was decreased by Ald-NaCl in both strains. Phosphorylation of epidermal growth factor receptor and extracellular signal-regulated kinase was increased by Ald-NaCl treatment in AT1aR-KO. Connective tissue growth factor (CTGF) and osteopontin mRNA were increased and accumulation of CTGF proteins was seen in the hearts of Ald-NaCl-treated AT1aR-KO. Ald-H2O-treated AT1aR-KO did not show any cardiac fibrosis. These results suggest that Ald-NaCl-induced cardiac fibrosis required both aldosterone and salt. Because cardiac fibrosis was exaggerated in Ald-NaCl-treated AT1aR-KO but was not seen in Wt treated with Ald-NaCl and olmesartan, AT1aR may not play a primary role in progression of cardiac fibrosis by Ald-NaCl, and gene disruption of AT1aR may have some implications in this model.

Relationship between volatile sulfur compounds in mouth air and systemic disease

This study examined the relationship between volatile sulfur compounds (VSCs), including hydrogen sulphide (H(2)S), methyl mercaptan (CH(3)SH) and dimethyl sulphide [(CH(3))(2)S], in mouth air of patients and a history of systemic disease. The subjects were 387 residents (174 males and 213 females) of Fukuoka Prefecture, Japan, who participated in an oral and systemic health survey for elderly persons (mean age: 61.8, s.d. 2.8 years). The VSCs were measured using a portable gas chromatograph (OralChroma). The H(2)S concentrations were significantly greater in the 132 subjects with a history of hypertension and the 41 subjects with a history of respiratory disease, including pneumonia, pulmonary emphysema and bronchitis, than in those without such a history. The CH(3)SH concentrations were significantly greater in those with a history of hypertension. The 16 subjects with a history of cerebrovascular disease, including intracerebral haemorrhage, cerebral infarction, and subarachnoid haemorrhage, and the 58 subjects with a history of liver disease, including hepatitis, alcoholic liver disease, drug-induced liver injury, fatty liver and liver cirrhosis, showed significantly greater (CH(3))(2)S concentrations (p < 0.05). These results suggest an association between the production of VSCs in mouth air and systemic diseases such as hypertension as well as respiratory, cerebrovascular and liver diseases.

Relationship between chewing ability and high-level functional capacity in an 80-year-old population in Japan

OBJECTIVES

To evaluate the association between high-level functional capacity and chewing in a middle-old community-based population.

BACKGROUND

Although basic and instrumental activities of daily living are known to be associated with chewing ability in the elderly, an association between higher levels of competence and chewing ability has not been evaluated in the elderly.

MATERIALS AND METHODS

The association between chewing ability using a number of different foods and high-level functional capacity by the Tokyo Metropolitan Institute of Gerontology was evaluated in 694, 80-year-old people residing in Fukuoka Prefecture, Japan.

RESULTS

A significant correlation was found, using multiple regression or logistic regression analyses adjusted for various confounding factors, between the number of total chewable foods, hard foods or moderately hard foods, and total functional capacity, instrumental activity, intellectual activity or social role ability. In contrast, the number of slightly hard foods, easily chewable foods and remaining teeth were only partly related to total functional capacity and intellectual activity.

CONCLUSION

High-level functional capacity including intellectual activity and social role in middle-old elderly was associated with the ability to chew hard foods than to chew easily chewable foods. Maintenance of chewing ability in elderly might result in better intellectual activity and social role.

Physical Fitness and 4-Year Mortality in an 80-Year-Old Population

BACKGROUND

Because little is known about the relationship between physical fitness and mortality among very elderly people, we evaluated this association in a Japanese population of 80-year-old community residents.

METHODS

Among 1282 80-year-old residents of Fukuoka Prefecture, Japan, 697 individuals (277 men and 420 women) underwent physical fitness tests of handgrip strength, isometric leg extensor strength, isokinetic leg extensor power, stepping rate, and one-leg standing time. Four years later, the dates and causes of death among the participants during those years were analyzed based on data from resident registration cards and from official death certificates.

RESULTS

During the 4-year follow-up period, 107 individuals (58 men and 49 women) died. Of these deaths, 27 were due to cardiovascular disease (CVD), 27 to cancer, 22 to pneumonia, and the rest to other causes. The relative hazard ratios (HR) for all-cause mortality, adjusted for various confounding factors, fell with increases in stepping rate, and the HR for pneumonia mortality fell with increases in leg extensor strength. In contrast, there was no association between cardiovascular or cancer mortality and physical fitness.

CONCLUSIONS

A partial association was found between impaired physical fitness at the age of 80 years and increased mortality in the 4 years thereafter. Mortality due to all causes was related only to stepping rate, and mortality due to pneumonia was related to leg extensor strength. Mortality due to CVDs or cancers was not associated with physical fitness.

Association Between Body Mass Index and Mortality in an 80-Year-Old Population

OBJECTIVES

To evaluate the association between body mass index (BMI) and all-cause mortality and cardiovascular disease (CVD) in an 80-year-old population.

DESIGN

Cohort study.

SETTING

Community-based.

PARTICIPANTS

Six hundred ninety-seven of 1,282 (54.4%) 80-year-old candidate individuals.

MEASUREMENTS

The dates and causes of all deaths were followed up for 4 years.

RESULTS

The relative hazard ratios (HRs) for all-cause mortality were lower in overweight subjects (BMI > or= 25.0) than in underweight (BMI<18.5) or normal-weight (BMI 18.5-24.9) subjects. Similarly, the HRs for mortality due to CVD in overweight subjects were 78% less (HR=0.22, 95% confidence interval (CI)=0.06-0.77) than those in underweight subjects, and those in normal weight subjects were 78% less (HR=0.22, 95% CI=0.08-0.60) than those in underweight subjects. Mortality due to CVD was 4.6 times (HR 4.64, 95% CI=1.68-12.80) as high in underweight subjects as in normal-weight subjects, and mortality due to cancers was 88% lower (HR=0.12, 95% CI=0.02-0.78) in the overweight group than in the underweight group. There were no differences in mortality due to pneumonia.

CONCLUSION

Overweight status was associated with longevity and underweight with short life, due to lower and higher mortality, respectively, from CVD and cancer.

Transient precordial ST elevation by a spasm of the conus artery during right coronary angiography

During coronary angiography of right coronary artery (RCA), a catheter wedged into a conus artery, and a remarkable coved-type ST elevation was seen in precordial lead through V1-3. LCA angiography did not show any abnormal findings, but we recognized a slow contrast flow in a conus artery by RCA angiography. The patient was free from chest pain, and a ST elevation was improved. The slow flow of a conus artery was recovered within five minutes. Precordial ST elevation may be caused by a catheter-induced spasm of a conus artery.

Role of percutaneous transhepatic obliteration for special types of varices with portal hypertension

The treatment of special types of varices with portal hypertension has not yet been established. We were able to control 13 cases of special types of varices by percutaneous transhepatic obliteration (PTO). These 13 cases consisted of 2 esophagojejunal varices after total gastrectomy for gastric cancer, 1 stoma varices after abdominoperineal excision for rectal cancer, 2 mesenteric varices with encephalopathy, 1 gastric variceal rupture, 1 gastrorenal and gastroazygos shunt with encephalopathy, 3 giant bar-type esophageal varices, 2 isolated gastric varices with gastropericardiac shunts, and 1 isolated gastric varices with gastrophrenic shunt. The special types of varices were successfully embolized in all cases and there were no complications. We conclude that the PTO is still an effective and safe treatment for special types of varices with portal hypertension.

Chronic administration of olmesartan attenuates the exaggerated pressor response to glutamate in the rostral ventrolateral medulla of SHR

It has been shown that the pressor responses to microinjection of L-glutamate in the rostral ventrolateral medulla (RVLM) are augmented in spontaneously hypertensive rats (SHR), and that these augmented responses are not altered by chronic conventional antihypertensive treatment. The aim of the present study was to determine the effect of chronic oral treatment with a new angiotensin II type 1 (AT(1)) receptor antagonist, RNH-6270 (the active form of olmesartan medoxomil), on cardiovascular responses to excitatory amino acids in the RVLM of SHR. SHR (12 weeks old) were treated with RNH-6270 (30 mg/kg/day) or vehicle for 4 weeks. At 16 weeks of age, L-glutamate (2 nmol), N-methyl-D-aspartate (NMDA; an ionotropic glutamate receptor agonist (20 pmol)), or (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid ((1S,3R)-ACPD; a metabotropic glutamate receptor agonist (1 nmol)) was microinjected into the RVLM of rats. The pressor responses to microinjection of L-glutamate or NMDA in the RNH-6270-treated SHR (+28.3 +/- 1.0 and +48.3 +/- 2.5 mm Hg, respectively) were significantly smaller than those in untreated SHR (+45.7 +/- 2.2 and +69.4 +/- 7.0 mm Hg, respectively, P < 0.05 each); however, they were still greater than those in the Wistar-Kyoto rats (+21.7 +/- 1.0 and +28.6 +/- 3.3 mm Hg, respectively, P < 0.05 each). In contrast, the augmented pressor responses to microinjection of (1S,3R)-ACPD in SHR were not affected by the RNH-6270 treatment. These results demonstrated that chronic oral treatment with RNH-6270, an AT(1) receptor antagonist, partly normalizes the pressor responses to L-glutamate or NMDA, but not (1S,3R)-ACPD, in the RVLM of SHR, suggesting that endogenous angiotensin II may be involved in the exaggerated pressor response to l-glutamate, probably through its ionotropic glutamate receptors.

Central and peripheral cardiovascular actions of apelin in conscious rats

APJ was cloned as an orphan G protein-coupled receptor and shares a close identity with angiotensin II type 1 receptor (AT1R). Apelin is a peptide that has recently been identified as an endogenous ligand of the APJ. Apelin and APJ mRNA are expressed in peripheral tissue and the central nervous system. However, little is known about the effects of apelin in cardiovascular regulation. To examine the central and peripheral role of apelin, we injected the active fragment of apelin [(Pyr1)apelin-13] intracerebroventricularly (ICV, 5 and 20 nmol, n=6) or intravenously (IV, 20 and 50 nmol, n=4 or 5) in conscious rats. ICV injection of (Pyr1)apelin-13 dose-dependently increased mean arterial pressure (MAP) and heart rate (HR) (19+/-3 mm Hg and 162+/-26 bpm at 20 nmol). Pretreatment with ICV injection of the AT1R antagonist (CV-11974, 20 nmol) did not alter the apelin-induced increase in MAP and HR. IV injection of (Pyr1)apelin-13 also dose-dependently increased MAP and HR (13+/-2 mm Hg and 103+/-18 bpm at 50 nmol); however, the peripheral effects of apelin were relatively weak compared to its central effects. Expression of c-fos in the paraventricular nucleus (PVN) of hypothalamus was increased in the rat that received ICV injection of (Pyr1)apelin-13 but not in the rat that received IV injection of (Pyr1)apelin-13. These results suggest that apelin plays a role in both central and peripheral cardiovascular regulation in conscious rats, and that the cardiovascular effects of apelin are not mediated by the AT1R.

Ghrelin Acts at the Nucleus of the Solitary Tract to Decrease Arterial Pressure in Rats

Ghrelin is an orexigenic peptide originally isolated from the stomach. Intracerebroventricular administration of ghrelin has been shown to elicit decreases in arterial pressure and renal sympathetic nerve activity in conscious rabbits. The aim of the present study was to determine the role of ghrelin in the brain stem in cardiovascular responses in rats. Unilateral microinjection of ghrelin into the nucleus of the solitary tract significantly decreased the mean arterial pressure and heart rate (-17.3+/-0.8 mm Hg and -13.6+/-3.5 bpm by 20 pmol). The microinjection of ghrelin into the nucleus of the solitary tract also suppressed the renal sympathetic nerve activity (-29.5+/-3.4%; P<0.0001). Pretreatment with intravenous injection of pentolinium (5 mg/kg), a ganglion-blocking agent, eliminated these cardiovascular responses induced by the microinjection of ghrelin (20 pmol) into the nucleus of the solitary tract; however, pretreatment with intravenous injection of atropine sulfate (0.1 mg/kg), an antagonist of muscarinic acetylcholine receptors, failed to prevent them. In contrast, unilateral microinjection of ghrelin into the area postrema, rostral, and caudal ventrolateral medulla caused no significant changes in the mean arterial pressure and heart rate. On the other hand, immunohistochemical study revealed that the receptor for ghrelin, the growth hormone secretagogue receptor, was expressed in the neuronal cells of the nucleus of the solitary tract and the dorsal motor nucleus of the vagus, but not in the cells of the area postrema. These results suggest that ghrelin acts at the nucleus of the solitary tract to suppress sympathetic activity and to decrease arterial pressure in rats.

Antisense to epidermal growth factor receptor prevents the development of left ventricular hypertrophy

We previously demonstrated that left ventricular hypertrophy (LVH) induced by angiotensin II infusion requires epidermal growth factor receptor (EGFR) activation to mediate the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway. To test whether the EGFR-mediated MAPK/ERK activation plays an important role in development and maintenance of LVH in spontaneously hypertensive rats (SHR), we investigated the effects of antisense oligodeoxynucleotide to EGFR (EGFR-AS) on LVH and blood pressure in young and adult SHR. EGFR-AS, sense oligonucleotide to EGFR (EGFR-S; 1.5 mg/kg), or vehicle control (5% dextrose) with liposome was injected once a week for 2 months in 5- or 13-week-old SHR. The effect of EGFR-AS on the expression of EGFR and phosphorylated ERK in the heart were examined by Western blots. After treatment, EGFR-AS significantly (P<0.05) decreased left ventricular weight/body weight and blood pressure in young SHR compared with EGFR-S or control-treated rats. In adult SHR, EGFR-AS did not affect left ventricular weight/body weight and blood pressure. EGFR and phosphorylated ERK significantly declined from 5 to 20 weeks (P<0.05). EGFR-AS, but not EGFR-S, significantly (P<0.05) decreased the expression of EGFR and phosphorylated ERK in young SHR, but had no significant effect in adult SHR. These results suggests that EGFR-mediated ERK activation is critically important for LVH in young SHR. This may be related to the high levels of EGFR and phosphorylated ERK in young SHR, suggesting a critical role of the EGFR-activated ERK pathway in cardiovascular development but not in the maintenance of established LVH in adult SHR.

Expression of angiotensin type 1 and 2 receptors in brain after transient middle cerebral artery occlusion in rats

Angiotensin II (Ang II) type 2 receptors (AT2Rs) have been associated with apoptosis. We hypothesized that AT2Rs are increased in stroke and may contribute effects of stroke to the brain. To test this, we have examined the expression of Ang II type 1 receptor (AT1R), AT2R and Ang II levels in the brain 24 h after transient middle cerebral artery occlusion (MCAO). The densities of AT1R and AT2R were measured by quantitative autoradiography (n=6). The levels of Ang II were measured by radioimmunoassay (RIA) (n=6) and by immunohistochemistry (n=3). AT1R levels on autoradiography showed a significant decrease (0.87+/-0.06 to 1.39+/-0.07 fmol/mg, p<0.01) in the ventral cortex of the stroke side compared to the cortices of non-stroke (NS) rats (n=4). There was no significant difference on ATIR in the contralateral verbal cortex of the stroke rats compared to NS control. In contrast, levels of AT2R in the ventral cortex of both the stroke and the contralateral sides were significantly increased (0.77+/-0.06, p<0.05 and 0.91+/-0.05, p<0.01 compared to 0.60+/-0.03 fmol/mg tissue, respectively). RIA showed that Ang II in the ventral cortex of both the stroke and the contralateral sides were significantly increased (241.63+/-47.72, p<0.01 and 165.51+/-42.59, p<0.05 compared to 76.80+/-4.10 pg/g tissue, respectively). Also, Ang II in the hypothalamus was significantly increased (179.50+/-17.49 to 118.50+/-6.65 pg/g tissue, p<0.05). Immunohistochemistry confirmed the increase of Ang II. These results demonstrate that brain Ang II and AT2Rs are increased whereas AT1Rs are decreased after transient MCAO in rats. We conclude that in stroke, Ang II and AT2R are activated and may contribute neural effects to brain ischemia.

Vigilant vectors: adeno-associated virus with a biosensor to switch on amplified therapeutic genes in specific tissues in life-threatening diseases

There are many life-threatening and chronic diseases in which physiological signals could be used to switch on therapeutic protective genes. We are developing a gene therapy approach in which a systemically injected "vigilant vector" waits for these signals and switches on genes to protect specific tissues with high amplification. The concept of a vigilant vector requires four components. The first component is a safe and stable vector that can be administered by systemic injection and express transgenes in a particular organ or tissue. The adeno-associated virus vector is safe and stable for this purpose. The second component is a reversible gene switch which is a biosensor that can detect certain physiological signals. We are developing a hypoxia switch, based on the oxygen-dependent degradation domain of hypoxia-inducible factor. The third component is a tissue-specific promoter, and we have used the myosin light-chain-2V promoter for specific expression in the heart. The fourth component is an amplification system. For this we have developed a double-plasmid/vector system based on the yeast GAL4 and human transcriptional activator p65 to produce a transactivating fusion protein that binds to a GAL4 activation sequence in an activating plasmid that then expresses high levels of cardioprotective genes.

Angiotensin II-induced cardiac hypertrophy and hypertension are attenuated by epidermal growth factor receptor antisense

BACKGROUND

Angiotensin II (Ang II) is a vasoconstrictor but also a growth factor. However, the Ang II type 1 receptor does not have a tyrosine kinase domain that mediates the cellular signals for mitosis. We have shown that Ang II acts via "trans"-activation of the epidermal growth factor receptor (EGFR) to induce activation of tyrosine kinase and mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) in vascular smooth muscle cells (VSMCs). To examine whether EGFR is involved in the development of left ventricular hypertrophy (LVH), we inhibited EGFR with a specific antisense oligodeoxynucleotide to attenuate the Ang II-induced cardiovascular hypertrophic effects.

METHODS AND RESULTS

The antisense oligodeoxynucleotide to EGFR (EGFR-AS) was designed and tested on Ang II-induced ERK activation in cultured VSMCs. We also investigated the effects of EGFR-AS on LVH and blood pressure (BP) in Ang II-infused hypertensive rats. In VSMCs, EGFR-AS (2.5 micromol/L) reduced EGFR expression and inhibited the Ang II-induced phosphorylation of ERK. In rats, Ang II (150 ng/h for 14 days) increased BP compared with controls (184+/-6 mm Hg versus 122+/-3 mm Hg; n=7; P<0.01). Continuous intravenous infusion of EGFR-AS (2 mg/kg) decreased BP (169+/-8 mm Hg; n=8; P<0.05). Ang II infusion increased the left ventricular/body weight (LV/BW) ratio compared with control rats (2.75+/-0.08 versus 2.33+/-0.07; P<0.01). EGFR-AS, but not EGFR-sense, normalized the LV/BW in Ang II-infused rats (2.32+/-0.06; P<0.01) and attenuated Ang II-enhanced EGFR expression and ERK phosphorylation.

CONCLUSION

Ang II requires EGFR to mediate ERK activation in VSMCs and the heart. EGFR plays a critical role in the LVH induced by Ang II.

Angiotensin II as a pro-inflammatory mediator

Angiotensin II (Ang II), the most important component of the renin-angiotensin system, is usually associated with hypertension and renal failure. Through its pro-inflammatory actions, it also plays an important role in each step of the development of atherosclerotic plaques and plaque rupture. Ang II stimulates the expression of nuclear factor-kappaB (NFkappaB), a transcription factor which regulates gene expression of inflammatory cytokines such as interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1). Ang II type 1 receptors (AT1) and angiotensin converting enzyme (ACE) are dramatically increased in atherosclerotic plaques, particularly in monocytes at the fibrous cap. Thus, in multiple ways, Ang II is a critical factor in atherosclerotic plaque formation, inflammation and plaque stability. ACE inhibitors and AT1R inhibitors could therefore be appropriate therapeutic agents in the treatment of atherosclerosis.

Vigilant vector: heart-specific promoter in an adeno-associated virus vector for cardioprotection

Repeated bouts of ischemia in the heart lead to fibrosis and eventually to heart failure. Although certain genes, such as SOD or hemoxygenase and antisense to AT(1)R, ACE, and (beta(1)-AR can provide short-term protection of the heart from ischemia, there is no known mechanism for constantly responding to repeated incidences of ischemia. We hypothesized that a "vigilant vector," designed to be expressed specifically in the heart and switch on therapeutic genes only during hypoxia, would provide cardioprotection. To attain cardiac specificity, we inserted an MLC2v promoter into an adeno-associated virus (AAV) designed to deliver AS to AT(1)R and gfp. In in vitro experiments in cardiomyocytes (H9C2 cells), the MLC2v-AAV-gfp drove gene expression in all cells at levels comparable to a cytomegalovirus (CMV) promoter. In in vivo experiments, the rAAV-MLC2v-gfp was injected intravenously into mice or rats. Green fluorescence protein (GFP) DNA was located in kidney, heart (right and left ventricle), lung, adrenal and spleen. GFP mRNA, however, was expressed only in the heart and absent in other tissues. To switch on the rAAV transgene during ischemia, we inserted a hypoxia response element (HRE). This upregulates transcription when O(2) levels are low. Thus, there are 4 components to the vigilant vector; a gene switch (HRE), a heart-specific promoter (MLC2v), a therapeutic gene (AS-AT(1)R) and a reporter gene (gfp). To silence or lower basal level of expression while retaining specificity, we have reduced the length of the MLC2v promoter from 3 kb to 1775 bp or 281 bp. The truncated promoter is equally effective in heart specific expression. Preliminary studies with the rAAV-HRE-gfp in vitro show an increased expression in 1% O(2) in 4 to 6 hours. By adding additional hypoxia-inducible factor (HIFalpha) (5 microg), the MLC2v-gfp expression is increased by 4-fold in 1% O(2). Further amplification of the gene to 400-fold in 1% O(2) can be achieved with a double plasmid. The construct may serve as a prototype "vigilant vector" to switch on therapeutic genes in specific tissue with physiological signals.

Magnesium decreases arterial pressure and inhibits cardiovascular responses induced by N-methyl-D-aspartate and metabotropic glutamate receptors stimulation in rostral ventrolateral medulla

OBJECTIVE

Magnesium sulfate (MgSO4) is widely used for the treatment of eclampsia. However, effects of Mg2+ in central cardiovascular regulation remain unclear. In the present study, the role of Mg2+ on cardiovascular regulation in the rostral ventrolateral medulla (RVLM) of rats was examined.

METHODS

Adult male Wistar rats were anesthetized with urethane, and artificially ventilated. The ventral surface of the medulla was exposed, and the RVLM was identified by microinjection (50 nl) of l-glutamate (l-Glu; 2 nmol). Then, MgSO4 (1, 3, 10 nmol, n = 7 for each dose) and magnesium chloride (MgCl2; 10 nmol, n = 7) were microinjected into the RVLM. l-Glu (2 nmol), N-methyl-D-aspartate (NMDA; 20 pmol), alpha-amino-3-hydroxy-5-methyl isoxazole-4-propionic acid (AMPA; 5 pmol) and (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid [(1S,3R)-ACPD, metabotropic glutamate receptor agonist; 1 nmol] were also microinjected with or without pretreatment of MgSO4 (10 nmol; n = 7 for each drug).

RESULTS

MgSO4 dose-dependently decreased mean arterial pressure (MAP) and heart rate (HR). The high dose of MgSO4 (10 nmol) significantly decreased MAP and HR (-25 +/- 4 mmHg and -43 +/- 6 bpm). Similarly, MgCl2 decreased MAP and HR (-27 +/- 4 mmHg and -30 +/- 6 bpm). The pressor response evoked by NMDA or (1S,3R)-ACPD was significantly attenuated by the pretreatment with MgSO4. In contrast, pressor response caused by l-Glu or AMPA was not affected by pretreatment with MgSO4.

CONCLUSIONS

These results suggest that Mg2+ has an inhibitory role on the RVLM neurons, and inhibits cardiovascular responses induced by NMDA and metabotropic glutamate receptor agonists.

Transcranial doppler sonography and ambulatory blood pressure monitoring in patients with hypertension

To appraise the value of transcranial Doppler sonography (TCD) for assessment of hypertensive cerebrovascular damage, the relationship between ambulatory blood pressure (BP) and indices of cerebral circulation determined by TCD was investigated. Subjects were 55 inpatients with or without hypertension, including 13 patients with histories of cerebrovascular attacks. Mean flow velocity (MFV) in the middle cerebral artery was measured by TCD, then the cerebrovascular resistance index (CVRI; mean BP/MFV) and the Fourier PI1 (pulsatility index of the first Fourier harmonic of the flow-velocity waveform) were determined as indices of cerebrovascular resistance. CO2 reactivity of MFV was estimated as an index of cerebrovascular flow reserve. CVRI positively correlated with both daytime and nighttime BP as well as with age (p<0.01). Fourier PI1 positively correlated with nighttime BP and age (p<0.01). CO2 reactivity did not correlate with any of the ambulatory BP parameters, but negatively correlated with age (p<0.01). LV mass index significantly correlated with ambulatory BP parameters, CVRI, and Fourier PI1 but did not correlate with CO2 reactivity. Multiple regression analyses showed that nighttime systolic BP was a significant correlate for CVRI and Fourier PI1, but not for CO2 reactivity, and that history of cerebrovascular attack was significant for CVRI and CO2 reactivity. We conclude that cerebrovascular resistance determined by TCD accords with the results of ambulatory BP and LVMI, and thus could be successfully used to detect the early stage of hypertensive cerebrovascular change. Cerebrovascular flow reserve would be relatively preserved in hypertensive patients without cerebrovascular diseases.

Antisense oligonucleotides strategy in the treatment of hypertension

Many kinds of drugs are used for the treatment of hypertension, but they are all short-acting (< or = 24 h) and patient compliance is poor. Gene therapy offers the advantage of producing long-term effects with high specificity, which should increase efficacy and reduce side effects. An antisense oligodeoxynucleotide (AS ODN) is a single-stranded oligonucleotide containing a gene-specific sequence of nucleotides, which is used to inhibit translation of mRNA. The application of AS ODNs for the treatment of hypertension began with targeting the renin-angiotensin system. Other genes, such as that coding for the beta1-adrenoceptor, have recently been targeted with AS ODNs in an attempt to reduce blood pressure. Strategies for the application of antisense technologies can be classified in two ways: the direct application of AS ODNs, and the production of AS by AS-cDNA inserted into viral vectors. Promising preclinical results from basic research have made feasible the possibility for antisense gene therapy of hypertension in the future.

MYOCARDIAL IMAGING WITH123I-METAIODOBENZYLGUANIDINE IN ESSENTIAL HYPERTENSION AND RENOVASCULAR HYPERTENSION

Iodine-123 metaiodobenzylguanidine (MIBG) myocardial imaging is considered to reflect cardiac sympathetic function. We performed myocardial MIBG scintigraphy and echocardiography in 27 patients with essential hypertension (EHT), 7 patients with renovascular hypertension (RVHT), and 8 normotensive subjects (NT) to investigate alterations in MIBG myocardial imaging in the presence of hypertension and left ventricular hypertrophy (LVH). EHT were divided into two groups based on LV wall thickness; EHT with LVH group (> or = 13 mm, n = 15) and EHT without LVH group (< 13 mm, n = 12). The delayed uptake of MIBG was decreased, and the washout rate of MIBG was greater in the EHT with LVH group than EHT without LVH group or NT group. The washout rate was correlated with LV mass and LV diastolic function (as assessed by mitral flow). In RVHT group, the MIBG washout rate increased even without LVH, compared with NT and EHT without LVH groups. In summary, the washout rate of MIBG increased in parallel with the development of LVH in EHT and increased independently of the LV mass in RVHT. Cardiac sympathetic function could be altered in hypertensive LVH and in renovascular hypertension.

The influence of chronic antihypertensive treatment on the central pressor response in SHR

We examined the influence of chronic antihypertensive treatment on the central pressor response in SHR. Adult male SHR were divided into 5 groups, i.e., those receiving 1) enalapril (Enal: 25 mg/kg/day in drinking water, n=12); 2) losartan (Los: 40 mg/kg/day, n=11); 3) candesartan (Cand: 4 mg/kg/day, n=12); 4) hydralazine+hydrochlorothiazide (H&H: 50+7.5 mg/kg/day, n=9); 5) vehicle (

CONTROL

n=9). At 4 weeks of treatment, hypertonic saline (0.25, 0.5 M) was intracerebroventricularly (i.c.v.) injected into conscious rats. Plasma catecholamines were measured before and after i.c.v. injection. On completion of the experiment, heart weight was measured, and angiotensin-converting enzyme (ACE) activity of the cerebrum was determined. All antihypertensive drugs elicited comparable reductions in systolic blood pressure, while heart rate was significantly higher in the H&H group than in the other groups during treatment. Pressor response to i.c.v. hypertonic saline (0.5 M) was significantly smaller in the Enal (12 +/- 3 mmHg) and Cand (11 +/- 2 mmHg) groups than in the Los (22 +/- 2 mmHg), H&H (16 +/- 2 mmHg), and CONTROL (29 +/- 5 mmHg) groups. Plasma catecholamines did not differ among the groups. Heart weight was lowest in the Enal group, followed by the Los and Cand groups. ACE activity of the cerebrum was significantly decreased in the Enal group. The results suggest that chronic treatment with various antihypertensive drugs differentially alters the central pressor response in SHR, and enalapril and candesartan are effective in attenuating this response.

Antisense inhibition of brain renin-angiotensin system decreased blood pressure in chronic 2-kidney, 1 clip hypertensive rats

The systemic renin-angiotensin system (RAS) plays an important role in blood pressure (BP) regulation during the development of 2-kidney, 1 clip (2K1C) hypertension. Its contributions decrease with time after constriction of the renal artery. During the chronic phase, the peripheral RAS returns to normal, but the hypertension is sustained for months. We hypothesized that in this phase the brain RAS contributes to the maintenance of high BP. To test the hypothesis, we studied the role of brain RAS by decreasing the synthesis of angiotensinogen (AGT) and the angiotensin II (Ang II) type 1a receptor (AT(1)R) with intracerebroventricular injections of antisense oligonucleotides (AS-ODNs). The response of systolic BP (SBP) to AS-ODNs to AGT mRNA was studied in 2K1C rats at 6 months after clipping, and the response to AS-ODNs to AT(1)R mRNA was studied at 10 months after clipping. Intracerebroventricular injection of AS-ODN-AGT (200 microgram/kg, n=5) significantly decreased SBP (-22+/-6 mm Hg, P<0.05) compared with the sense ODN (n=5) and saline (n=3) groups. Intracerebroventricular injection of AS-ODN-AGT reduced the elevated hypothalamic Ang II level. The hypothalamic Ang II content in sense ODN and saline groups was significantly (P<0.05) higher than in the nonclipped group. Compared with inverted ODN, intracerebroventricular injection of AS-ODN-AT(1)R (250 microgram/kg, n=6) significantly decreased SBP (-26+/-8 mm Hg, P<0.05) for 3 days after injection. This was a brain effect because intravenous AS-ODN-AT(1)R at a dose of 250 to 500 microgram/kg did not affect SBP. These results suggest that the brain RAS plays an important role in maintaining the elevated SBP in chronic 2K1C hypertension.

The multiple actions of angiotensin II in atherosclerosis

Angiotensin II (Ang II), the effector peptide of the renin-angiotensin system, has been implied in the pathogenesis of atherosclerosis on various levels. There is abundant experimental evidence that pharmacological antagonism of Ang II formation by angiotensin converting enzyme inhibition or blockade of the cellular effects of Ang II by angiotensin type 1 receptor blockade inhibits formation and progression of atherosclerotic lesions. Angiotensin promotes generation of oxidative stress in the vasculature, which appears to be a key mediator of Ang II-induced endothelial dysfunction, endothelial cell apoptosis, and lipoprotein peroxidation. Ang II also induces cellular adhesion molecules, chemotactic and proinflammatory cytokines, all of which participate in the induction of an inflammatory response in the vessel wall. In addition, Ang II triggers responses in vascular smooth muscle cells that lead to proliferation, migration, and a phenotypic modulation resulting in production of growth factors and extracellular matrix. While all of these effects contribute to neointima formation and development of atherosclerotic lesions, Ang II may also be involved in acute complications of atherosclerosis by promoting plaque rupture and a hyperthrombotic state. Accordingly, Ang II appears to have a central role in the pathophysiology of atherosclerosis.

Cardiovascular responses to glutamate and angiotensin II in ventrolateral medulla of hypertension induced by chronic inhibition of nitric oxide

It has been suggested that nitric oxide (NO) influences the actions of L-glutamate and angiotensin II in the brain. In the present study, we examined whether cardiovascular responses to L-glutamate and angiotensin II would be altered in the rostral ventrolateral medulla (RVLM) of rats treated with an NO synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME). Wistar rats were treated with either L-NAME (100 mg/kg/day, n=9) or vehicle (n=8) for 4 weeks. L-glutamate (2 nmol/50 nl) or angiotensin 11 (100 pmol) was then microinjected into unilateral RVLM of anesthetized rats. Upon completion of the experiments, angiotensin-converting enzyme (ACE) activity of the brain stem was measured. The systolic blood pressure after 4 weeks of the treatment was significantly higher in the L-NAME group (203+/-8 mmHg) than in the control group (142+/-3 mmHg, p< 0.01). The pressor response to L-glutamate microinjected into the RVLM was significantly greater in the L-NAME group (31+/-2 mmHg) than in the control group (24+/-1 mmHg, p< 0.01). Similarly, angiotensin II showed a greater pressor response in the L-NAME group. ACE activity of the brain stem did not differ between the groups. In conclusion, NO may have an inhibitory influence on the actions of L-glutamate and angiotensin II in the RVLM.

Metabotropic glutamate receptor subtypes involved in cardiovascular regulation in the rostral ventrolateral medulla of rats

We have previously reported that metabotropic glutamate receptors (mGluR) participate in cardiovascular regulation in the rostral ventrolateral medulla (RVLM) of rats. In the present study, we have tried to elucidate which subtype of mGluR contributes to cardiovascular responses elicited by L-glutamate in the RVLM. Adult male Wistar rats (348 +/- 11 g, n = 21) were anesthetized and artificially ventilated. Microinjections of agonists and antagonists for each mGluR subtype were done into unilateral RVLM. Each of group I, II and III mGluR agonist (1 nmol/50 nl) produced significant increases in arterial pressure (18 +/- 2, 9 +/- 2 and 34 +/- 3 mmHg, respectively) and heart rate (18 +/- 4, 13 +/- 3 and 33 +/- 12 bpm, respectively). Microinjections of group I, II and III mGluR antagonists failed to inhibit the cardiovascular responses induced by subsequently injected agonists. However, group I antagonist [(RS)-1-aminoindan-1,5-dicarboxylic acid] elicited transient increases in arterial pressure and heart rate, followed by decreases in both variables (-19 +/- 4 mmHg and -22 +/- 4 bpm). These results suggest that all of three subtypes of mGluR participate in cardiovascular responses induced by L-glutamate, and group I mGluR may play an important role in the maintenance of arterial pressure.

Central infusion of L-arginine or superoxide dismutase does not alter arterial pressure in SHR

Cardiovascular responses to L-arginine and nitric oxide (NO) are augmented in the rostral ventrolateral medulla (RVLM) of spontaneously hypertensive rats (SHR), and the intravenous injection of superoxide dismutase (SOD) mimetic decreases the arterial pressure in these rats. In the present study, we examined whether the chronic central infusion of L-arginine or an SOD mimetic would reduce the blood pressure of SHR and alter responses to an NOS inhibitor or an NO donor in the RVLM. For this purpose, we administered L-arginine (SHR-Arg: 13.2 micromol/day, n=6), a stable membrane-permeable SOD mimetic, 4-hydroxy-2, 2,6,6-tetramethyl piperidine-1-oxyl (tempol) (SHR-Temp: 13.2 micromol/day, n=6), or vehicle (SHR-C: n=6) into the lateral ventricle of 12-week-old SHR for 2 weeks. When the rats reached 14 weeks of age, N(G)-nitro-L-arginine methyl ester (L-NAME: 10 nmol/50 nl) or NOC 18 (NO donor: 10 nmol/50 nl) was microinjected into the unilateral RVLM. Blood pressure did not decrease in any of the treatment groups (SHR-Arg: 209+/-4 mmHg, SHR-Temp: 210+/-6 mmHg, SHR-C: 197+/-6 mmHg). The microinjection of L-NAME into the RVLM induced a significant increase in the mean arterial pressure (MAP) (SHR-Arg: 10-4 mmHg, SHR-Temp: 12+/-4 mmHg, SHR-C: 11+/-3 mmHg), and the increases in MAP did not differ among the groups. The micro-injection of NOC 18 reduced MAP (SHR-Arg: -12+/-2 mmHg, SHR-Temp: -15+/-3 mmHg, SHR-C: -13+/-3 mmHg), and the depressor responses were comparable among groups. These results do not support the hypothesis that chronic L-arginine deficiency or the enhanced degeneration of NO by superoxide radicals in the central nervous system contributes to the maintenance of arterial pressure in SHR.

Natriuretic effect of barnidipine, a long-acting dihydropyridine calcium channel blocker, in patients with essential hypertension

OBJECTIVE

To evaluate the effect of barnidipine hydrochloride, a long-acting dihydropyridine calcium channel blocker on urinary sodium excretion in patients with essential hypertension.

PATIENTS

Twelve patients (2 males, 10 females) with mild to moderate essential hypertension.

METHODS

A single-blinded study. After the control (placebo) period, 10 to 15 mg barnidipine hydrochloride was administered for 7 days, followed by a post-treatment (placebo) period. Daily changes in blood pressure, urinary volume, and urinary electrolyte excretions were evaluated. Plasma levels of atrial natriuretic peptide (ANP) and aldosterone were also determined in each period. Daily sodium intake was kept at 120 mEq.

RESULTS

Blood pressure decreased from 161 +/- 4/92 +/- 2 mmHg to 146 +/- 4/85 +/- 2 mmHg (p<0.05) after 7-day-treatment with barnidipine. Barnidipine significantly increased urinary sodium excretion; the change was evident on the first day of administration (control period 41 +/- 3 mEq/day, and first day 59 +/- 3 mEq/day, p < 0.05). Drug discontinuation transiently decreased sodium excretion to 35 +/- 3 mEq/day. Cumulative sodium balance after 7-day-treatment reached 47 +/- 19 mEq. Urine volume, potassium excretion, and creatinine excretion did not change during the treatment period. The plasma levels of ANP tended to increase, but those of aldosterone did not change with barnidipine.

CONCLUSION

Barnidipine administration for a week decreased the blood pressure and made the sodium balance negative by increasing the urinary sodium excretion in patients with essential hypertension. The natriuretic effect of this drug could contribute at least in part to its antihypertensive effect.

Subtypes of metabotropic glutamate receptors in the nucleus of the solitary tract of rats

We have determined the role of subgroups of metabotropic glutamate receptors (mGluRs) in the nucleus of the solitary tract (NTS) of normotensive Wistar rats. Unilateral microinjection of (S)-3, 5-dihydroxyphenylglycine (3,5-DHPG), an agonist of group I mGluRs, into the NTS significantly decreased mean arterial pressure (MAP), heart rate (HR), and renal sympathetic nerve activity (RSNA) (-19. 4+/-2.6 mmHg, -16.4+/-5.1 beats/min, and -30.6+/-5.7% by 1 nmol). Microinjection of (R,S)-1-aminoindan-1,5-dicarboxylic acid (AIDA; 1 nmol), a putative antagonist of group I mGluRs, into the NTS caused transient decreases in MAP and RSNA, followed by sustained increases in MAP (+8.3+/-2.4 mmHg) and RSNA (+27.7+/-10.8%). Pretreatment with AIDA failed to prevent the cardiovascular and RSNA responses to microinjection of 3,5-DHPG. Unilateral microinjection of (S)-4-carboxy-3-hydroxyphenylglycine (4C3HPG), an agonist of group II mGluRs, into the NTS also significantly decreased MAP, HR, and RSNA, whose responses were not inhibited by pre-microinjection of (2S)-alpha-ethylglutamic acid (EGLU; 2 nmol), a putative antagonist of group II mGluRs. On the other hand, unilateral microinjection of L(+)-2-amino-4-phosphonobutyric acid (L-AP4), an agonist of group III mGluRs, into the NTS caused dose-related decreases in MAP (-8. 3+/-1.5 mmHg by 0.1 nmol and -45.1+/-3.4 mmHg by 0.3 nmol), HR, and RSNA (-21.3+/-3.9% by 0.1 nmol and -77.2+/-6.5% by 0.3 nmol), whose responses were suppressed by pre-microinjection of (R, S)-alpha-cyclopropyl-4-phosphonophenylglycine (CPPG; 0.3 nmol), an antagonist of group III mGluRs. These results suggest that all subgroups of mGluRs participate in cardiovascular and sympathetic regulations in the NTS of rats, and that endogenous group I mGluRs in the NTS may contribute to tonic cardiovascular and sympathetic regulations.

Minimal-change nephrotic syndrome and acute renal failure in a patient with aged onset insulin-dependent diabetes mellitus and autoimmune thyroiditis

A 61-year-old woman with a 2-year history of insulin-dependent diabetes mellitus (IDDM) developed nephrotic syndrome. Renal biopsy showed minimal-change nephrotic syndrome (MCNS), and no evidence of diabetic glomerulosclerosis. Although steroid therapy was initiated, plasma urea and creatinine rose and hemodialysis was required. After 4 weeks, she responded to steroids and her renal function returned to normal. MCNS, which is not associated with diabetic glomerulosclerosis, has rarely been seen in IDDM patients with nephrotic syndrome. Her human leukocyte antigen typing was A24, BW52, BW61, DR2 and DR9. This typing has been reported to be associated with both IDDM and renal disease.

Effects of chronic oral treatment with imidapril and TCV-116 on the responsiveness to angiotensin II in ventrolateral medulla of SHR

OBJECTIVE

To examine whether chronic oral treatment with an angiotensin-converting enzyme inhibitor imidapril and an angiotensin II type 1 receptor antagonist TCV-116 would alter the response to angiotensin II in the rostral ventrolateral medulla.

METHODS

Twelve-week-old spontaneously hypertensive rats (SHR) were treated with imidapril (20 mg/kg per day, n = 7), TCV-116 (5 mg/kg per day, n = 8) or vehicle (n = 8) for 4 weeks. Wistar- Kyoto rats (WKY) (n = 8) served as normotensive controls. At 16 weeks of age, angiotensin II (100 pmol) was microinjected into the rostral ventrolateral medulla of anaesthetized rats.

RESULTS

Blood pressure decreased significantly in the rats treated with either imidapril or TCV-116. Pressor responses to angiotensin II microinjected into the rostral ventrolateral medulla were comparable in the untreated SHR, the imidapril-treated SHR and WKY (12 +/- 2, 15 +/- 4 and 10 +/- 1 mmHg, respectively), but were abolished in SHR treated with TCV-116 (0 +/- 2 mmHg, P< 0.01). Angiotensin-converting enzyme activity in the brain stem was significantly lower in SHR treated with imidapril (0.70 +/- 0.06 nmol/mg per h), but significantly higher in SHR treated with TCV-116 (1.62 +/- 0.04 nmol/mg per h) than in the untreated SHR (1.37 +/- 0.05 nmol/mg per h).

CONCLUSIONS

Chronic oral treatment with imidapril and TCV-116 may have divergent influences on the renin-angiotensin system within the brain stem. TCV-116, but not imidapril, abolishes the pressor effect of angiotensin II in the rostral ventrolateral medulla.

Chaos and spectral analyses of heart rate variability during head-up tilting in essential hypertension

To investigate nonlinear and linear components of heart rate variability (HRV) in essential hypertension (EHT), we analyzed HRV by chaos and spectral analyses in patients with EHT (n = 18) and normotensives (n = 10) during head-up tilting. We used the correlation dimension (CD) and Lyapunov exponents as the parameters of chaos. The CD, an index of complexity, was lower at rest in EHT group than in normotensives, and did not change in EHT group in response to head-up tilting, but decreased in normotensives. Head-up tilting did not change the Lyapunov exponents, an index of sensitive dependence on initial condition, a hallmark of chaos, in both groups. In the spectral analysis, the normalized high-frequency component (%HF) was decreased in EHT group at rest, and head-up tilting increased the low- to high-frequency ratio (L/H) and reduced the %HF in both groups. The CD and Lyapunov exponents at rest were correlated with the %HF and L/H. These results suggest that chaos analysis can assess the different aspect of HRV from spectral analysis and that nonlinear components of HRV may be associated with hypertension through an impaired dynamic regulation of HRV.

Antisense inhibition of angiotensinogen attenuates vasopressin release in the paraventricular hypothalamic nucleus of spontaneously hypertensive rats

It has been reported that intracerebroventricularly injected antisense oligonucleotide to angiotensinogen reduces arterial pressure in spontaneously hypertensive rats (SHR), but the mechanism and the sites of action remain unclear. In the present study, we examined whether injection of antisense oligonucleotide to angiotensinogen into the paraventricular hypothalamic nucleus (PVN) would influence arterial pressure and vasopressin release. For this purpose, 12-week-old male SHR were cannulated into the bilateral PVN. One week later, we injected antisense or sense oligonucleotide to angiotensinogen into the bilateral PVN (0.2 nmol/200 nl each side). After 24 h, we directly monitored arterial pressure, and then took blood samples to measure plasma vasopressin, catecholamines and renin activity. Mean arterial pressure did not change in either group (from 144+/-3 to 154+/-4 mmHg for the antisense oligonucleotide group, n=11; from 147+/-4 to 156+/-3 mmHg for the sense oligonucleotide group, n=11). Antisense oligonucleotide attenuated vasopressin release compared with sense oligonucleotide (1.30+/-0.28 vs. 3.29+/-0.60 pg/ml, respectively, P<0.01). Plasma catecholamines also decreased in the antisense oligonucleotide group compared with the sense oligonucleotide group. However, the plasma renin activity did not differ between the groups. In the additional experiment, we examined the neurohormonal and cardiovascular effects of intracerebroventricularly injected antisense oligonucleotide to angiotensinogen in SHR. Mean arterial pressure, plasma vasopressin and plasma norepinephrine were significantly lower in the antisense oligonucleotide group than in the sense oligonucleotide group. These results suggest that angiotensinogen in PVN plays important roles in vasopressin release and sympathetic nerve activity, but may not contribute to the maintenance of arterial pressure in SHR.

Central and peripheral mechanisms involved in hypertension induced by chronic inhibition of nitric oxide synthase in rats

OBJECTIVE

To study the possible central and peripheral mechanisms involved in hypertension induced by chronic inhibition of nitric oxide synthase.

METHODS

We evaluated neurohormonal and renal responses of Wistar rats to chronic oral administration of 20 and 100 mg/kg per day NG-nitro-L-arginine methyl ester (L-NAME). Effects of intracerebroventricular and intravenous injections of NO donors (NOC-18 and FK-409) and an angiotensin II type 1 receptor antagonist CV-11974, and intravenous injection of alpha-adrenergic receptor antagonist phentolamine after chronic treatment with 100 mg/kg per day L-NAME were also studied.

RESULTS

The chronic treatment with L-NAME induced a sustained dose-dependent hypertension with a decrease in heart rate. Urinary levels of norepinephrine and epinephrine decreased with no changes in plasma catecholamine levels, renin activity, and vasopressin level. Serum nitrate/nitrite levels in the rats treated with the high dose of L-NAME decreased. The intracerebroventricular and intravenous injections of the NO donors reduced arterial pressure in L-NAME-treated rats to a significantly greater extent than they did that in control rats. The intravenous but not intracerebroventricular injection of CV-11974 produced a sustained decrease in arterial pressure of L-NAME-treated rats. The depressor responses to intravenous injection of phentolamine of L-NAME-treated and control rats were similar.

CONCLUSIONS

Results indicate that L-NAME-induced hypertension is associated with a deficiency of nitric oxide, both peripherally and centrally. Circulating angiotensin II could contribute to the maintenance of hypertension via angiotensin II type 1 receptor while the sympathetic nervous system seems to be suppressed.

Role of nitric oxide in the nucleus of the solitary tract of rats

We have determined the role of nitric oxide (NO) in the nucleus of the solitary tract (NTS) of normotensive Wistar rats. The unilateral microinjection of Nomega-nitro-l-arginine methyl ester (10 nmol) to block the synthesis of NO into the NTS significantly decreased the arterial pressure, heart rate (HR) and renal sympathetic nerve activity (RSNA) (-19+/-2 mmHg, -23+/-5 beats/min, -30+/-2%, respectively). The microinjection of carboxy-2-phenyl-4,4,5, 5-tetramethylimidazoline-1-oxyl 3-oxide (Carboxy PTIO) (trapper of NO; 0.1 nmol) into the NTS also decreased arterial pressure and RSNA. Conversely, the microinjection of Et2N[N(O)NO]Na (NOC 18) (NO donor; 10 nmol) caused increases in arterial pressure, HR and RSNA (+14+/-2 mmHg, +11+/-2 beats/min, +38+/-7%, respectively), which was inhibited by the pre-microinjection of Carboxy PTIO (0.1 nmol). On the other hand, not only l-arginine (10 nmol) but also d-arginine (10 nmol), which is inactive to produce NO, significantly decreased the arterial pressure and RSNA. These results suggest that (1) NO acts at the NTS to increase the arterial pressure and RSNA, and (2) the microinjection of l-arginine as well as d-arginine led to decreases in arterial pressure and RSNA that were not mediated by the formation of NO in the NTS.

Single L-type calcium channels in smooth muscle cells from resistance arteries of spontaneously hypertensive rats

The amplitude of the whole-cell L-type Ca2+ channel current recorded from vascular smooth muscle cells is reportedly greater in spontaneously hypertensive rats (SHR) than in Wistar-Kyoto rats (WKY). However, no study has examined properties of single Ca2+ channels in arterial cells from these strains. To further test the hypothesis that activation of L-type Ca2+ channels in arterial smooth muscle cells would be enhanced in SHR, we recorded single Ca2+ channel currents in resistance mesenteric artery cells from SHR and WKY (8 to 9 weeks of age) using a cell-attached patch clamp technique. With 50 mmol/L Ba2+ in the recording pipette, the depolarizing pulse from a holding potential of -40 mV evoked the single L-type Ca2+ channel current. Opening of the single channels was more frequent in cells from SHR than from WKY. Single-channel conductance (20 pS) and open time (1 ms at 0 mV) did not differ in the two strains. The results suggest that an increased amplitude of the whole-cell current can be attributed to the enhanced opening of single Ca2+ channels in the arterial smooth muscle cells from SHR compared with WKY.

Enhanced depressor response to nitric oxide in the rostral ventrolateral medulla of spontaneously hypertensive rats

Possible impairment of the L-arginine-nitric oxide (NO) pathway in the rostral ventrolateral medulla of adult spontaneously hypertensive rats (SHR) was investigated by microinjecting N(G)-nitro-L-arginine methyl ester (L-NAME), NOC 18 (an NO donor), or L-arginine. Unilateral injection of L-NAME (10 nmol/50 nL) into the rostral ventrolateral medulla significantly increased mean arterial pressure (MAP) in both SHR and Wistar-Kyoto rats (WKY). The increases in MAP did not differ significantly between the two strains (15+/-3 versus 10+/-2 mm Hg, respectively; n=8). In contrast, microinjection of L-arginine elicited significant (P<.05) dose-dependent decreases in MAP in both strains, and these depressor responses were significantly greater in SHR than in WKY (in 10 nmol of L-arginine: -29+/-2 versus -15+/-2 mm Hg, respectively; n=8, P<.01). Similarly, microinjection of NOC 18 (10 nmol/50 nL) reduced MAP in both strains, and the depressor response was also significantly greater in SHR than in WKY (-38+/-7 versus -22+/-3 mm Hg, respectively; n=8, P<.05). These results suggest that the L-arginine-NO pathway in the rostral ventrolateral medulla is impaired in SHR and that this impairment may contribute to the increase in arterial pressure in this animal model of genetic hypertension.

Asymptomatic moyamoya disease associated with coronary and renal artery stenoses--a case report

Moyamoya disease is an occlusive intracranial arteriopathy with abnormal cerebral vascular collateral networks. Although this disease is known to be associated with stenosis of extracranial arteries, such as the renal artery, a case associated with stenoses of the coronary and renal arteries has not been reported. We described here a 23-year-old man who had effort angina, renovascular hypertension, and asymptomatic moyamoya disease. Arterioangiography revealed bilateral occlusion of the intracranial carotid arteries and stenoses in the left coronary artery and the left renal artery.

Antihypertensive treatment and the responsiveness to glutamate in ventrolateral medulla

We have recently reported that the cardiovascular responses to excitatory amino acids are augmented in the rostral ventrolateral medulla of spontaneously hypertensive rats (SHR). In the present study, we investigated whether the responsiveness to excitatory amino acids would be normalized by antihypertensive treatment. Thus we treated 4-week-old SHR and age-matched Wistar-Kyoto (WKY) rats with either enalapril (25 mg/kg per day in drinking water) or vehicle for 8 weeks. At 12 weeks of age, systolic blood pressure in the untreated SHR (248+/-9 mm Hg) was significantly (P<.01) higher than that in the enalapril-treated SHR (140+/-4 mm Hg), untreated WKY rats (148+/-4 mm Hg), and enalapril-treated WKY rats (117+/-1 mm Hg). The pressor responses to L-glutamate (2 nmol) microinjected into the rostral ventrolateral medulla were similar in enalapril-treated and untreated SHR (40+/-5 and 47+/-3 mm Hg, respectively, NS), and these responses were significantly greater than that seen in the untreated WKY rats (24+/-2 mm Hg, P<.01). On the other hand, the pressor response to either N-methyl-D-aspartate, an ionotropic glutamate receptor agonist, or (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid, a metabotropic glutamate receptor agonist, in the enalapril-treated SHR was slightly but significantly smaller than that in the untreated SHR but was still markedly greater than those in untreated and enalapril-treated WKY rats. These results suggest that the augmented responsiveness to excitatory amino acids in the rostral ventrolateral medulla of SHR may be at least partly genetically determined and cannot be normalized by the treatment with enalapril.