Antiatherogenic action of nitrendipine in hypercholesterolemic rabbits: changes in aortic macrophage accumulation and smooth muscle cell phenotype

Intimal accumulation of macrophages and changes in the phenotype and growth properties of vascular smooth muscle cells (SMCs) represent key events in the development of atherosclerotic lesions. Here we report on the in vivo effect exerted by nitrendipine on aortic tissue of cholesterol-fed rabbits. We have focused especially on the myosin heavy chain (MyHC) pattern expressed by aortic SMC, taken as a marker of cell differentiation. Using monoclonal antibodies specific to the different forms of MyHC, three differentiation steps were determined: adult, postnatal, and fetal. Nitrendipine administered in conjunction with a cholesterol-enriched diet reduced the development of atherosclerotic lesions (atherosclerosis index: 0.21 vs. 0.32 in untreated animals, p< 0.005), despite persistently high serum cholesterol levels. Compared to untreated controls, nitrendipine-treated animals displayed a decreased number of postnatal-type SMCs in the media underlying the plaque (prevalence index: 0.07 vs. 0.26, p < 0.0001 and a lower aortic cholesterol content (free cholesterol: 3.3 vs. 11.5 ng/mg, p< 0.0001; esterified cholesterol: 7.2 vs. 40.5 ng/mg, p< 0.0001). Moreover, nitrendipine treatment decreased the intimal accumulation of macrophages and fetal-type SMCs. It is conceivable that calcium antagonists may exert their antiatherogenic effect, at least in part, through cellular changes unrelated to the classical risk factors.

[The relationship between cell membrane adrenoreceptor response and insulinemia in hypertension patients undergoing calcium antagonist treatment]

Dynamics of correlations between the absolute values and individual changes in adrenoception of erythrocytes and insulinemia was studied in 17 patients with hypertension (II stage) prior to and after 2-month treatment by calcium antagonists. Clear correlation is observed between the sensitivity of alpha- and beta- adrenoceptors and reduction of insulinemia after treatment with calcium antagonists (r = -0.77, p < 0.05). The effect of heterologous sensitization of cell membranes on metabolism in patients suffered with hypertonia after their treatment with calcium antagonists are discussed.

Nitrendipine treatment in women with polycystic ovarian syndrome: evidence for a lack of effects of calcium channel blockers on insulin, androgens, and sex hormone-binding globulin

It has been shown that in vitro calcium channel blockers may regulate insulin secretion, and in vivo studies have demonstrated that they can reduce the degree of hyperinsulinemia and ameliorate the insulin-resistant state in subjects (particularly men) with obesity and hypertension. It is also commonly accepted that hyperinsulinemia may be an important factor responsible for the development of hyperandrogenism in obese women with polycystic ovarian syndrome (PCOS). We, therefore, investigated whether the administration of nitrendipine, a widely used calcium channel blocker, may improve both insulin levels and hyperandrogenism in a group of seven insulin-resistant hyperinsulinemic women with obesity and PCOS. They were treated for 7-8 days with oral nitrendipine (10 mg, twice daily) or placebo using a double blind, cross-over design. Before and after treatment, blood samples were obtained for androgen and sex hormone-binding globulin determinations, and an oral glucose tolerance test was performed, measuring glucose and insulin. Both nitrendipine and placebo failed to decrease basal and stimulated insulin levels. Moreover, no significant variations in testosterone, dehydroepiandrosterone sulfate, or sex hormone-binding globulin concentrations were observed after either treatment. Therefore, these data fail to support previous suggestions that calcium channel blockers may play a role in the treatment of hyperandrogenism and hyperinsulinemia in obese women with PCOS.

Effect of indomethacin on blood pressure control during treatment with nitrendipine

This study tested the hypothesis that treatment with a nonsteroidal anti-inflammatory drug will not alter the hypotensive effect of a dihydropyridine calcium channel antagonist. Fifteen essential hypertensives (ages 58-80 years) had a supine diastolic blood pressure (DBP) < 100 mmHg after 4 weeks monotherapy with nitrendipine 5-20 mg twice daily. They entered a double-blind randomised crossover study in which the addition of indomethacin 25 mg three times daily was compared with placebo in treatment phases each of 4 weeks duration. Subjects were seen weekly and measurements in the last 2 weeks of each phase were compared. Supine blood pressure (mean +/- SE) was higher in the indomethacin phase (158 +/- 4/80 +/- 2) than in the placebo phase (154 +/- 4/76 +/- 3) (p < 0.01 for DBP). In 6/15 (40%) of subjects the increase in supine diastolic blood pressure with indomethacin was > 5 mmHg. Plasma urea was also increased in the indomethacin phase: 7.6 +/- 0.6 mmol/l compared with placebo: 6.3 +/- 0.5 mmol/l (p < 0.001). The study has demonstrated that concurrent treatment with the NSAID indomethacin impairs the blood pressure lowering effect of the dihydropyridine calcium channel antagonist nitrendipine. This increase in blood pressure with indomethacin in subjects treated with nitrendipine may represent either an independent pressor effect of indomethacin or a reduced vasodilator prostanoid contribution to the hypotensive effect of nitrendipine. This blood pressure increase may be sufficient to interfere significantly with clinical blood pressure control in some subjects.

Protection of CCL4-induced liver damage in rats by some calcium channel blockers

Liver necrosis was produced in rats by administering 3 doses o a mixture o carbon tetrachloide+olive oil, 2 ml/kg, ip. The liver damage was evidenced by the elevated levels serun aspartate aminotrans ferase (AST), alanine aminotransferase (AIT) and gamma glutamyl transpeptidase (gamma-GT) and by histopathological observations of liver sections. Nitrendipine, nimodipine and nisoldipine (1 mg/100 g of rat, ip) significantly reduced these elevated levels of AST, AIT and gamma-GT. Carbon tetrachloride induced liver necrosis was also found to be significantly reduced in nitrendipine, nimodipine and nisoldipine pre-treated animals as observed macroscopically and histologically.

A multicenter, randomized, double-blind, placebo-controlled, two-year trial to study the effect of nitrendipine on chronic renal transplant function

The ongoing multicenter, randomized, double-blind, placebo-controlled trial investigates the effect of nitrendipine on kidney function after renal transplantation. Renal transplant recipients (6th-12th postoperative week, serum creatinine < 3 mg/dl) were divided into a normotensive (diastolic blood pressure < 90 mmHg) and a hypertensive group (diastolic blood pressure > or = 90, < 115 mmHg). Normotensive patients are randomly treated for 104 weeks with nitrendipine 2 x 5 mg daily or placebo, hypertensive patients with 2 x 10 mg - 2 x 20 mg nitrendipine daily or placebo and in case of inefficacy with additional antihypertensive drugs. Primary end point of the study is the renal transplant function. The trial was started in June 1990. One hundred and eight patients were included into the normotensive and 138 patients into the hypertensive group. Renal allograft function, cyclosporine trough levels and the donor characteristics were not different between the normotensive and hypertensive groups at entry into the study. After 12 months there was no significant change of renal transplant function in both groups. Cyclosporine trough levels were also similar in the normotensive and hypertensive group after 12 months. As expected, blood pressure decreased significantly after 12 months from 150 +/- 17/95 +/- 11 mmHg to 141 +/- 16/90 +/- 9 mmHg in the hypertensive group (p < 0.01). In contrast, in the normotensive group blood pressure increased significantly from 128 +/- 12/80 +/- 6 mmHg to 135 +/- 15/86 +/- 8 mmHg (p < 0.001). No normotensive but 4 hypertensive patients developed graft failure during the first 12 months of the study.

Treatment in hypertensive cardiac hypertrophy, I. Neuropeptide Y and beta-adrenoceptors

In the present study, we investigated serum and myocardial neuropeptide Y concentrations as measures of sympathetic activity as well as myocardial beta-adrenoceptors and beta-adrenoceptor-stimulated adenylyl cyclase activity in spontaneously hypertensive rats (SHR). SHR and control rats at 10 weeks of age were kept on oral treatment with captopril, nitrendipine, or both for 20 weeks. Treatment only slightly reduced but did not normalize blood pressure and cardiac hypertrophy in SHR. The elevated serum concentration of neuropeptide Y, the reduced number of beta-adrenoceptors, and the depressed beta-adrenoceptor-stimulated adenylyl cyclase activity were partly normalized compared with the values observed in control rats. We conclude that antihypertensive treatment, at doses that failed to normalize systolic pressure and to reverse cardiac hypertrophy completely, is able to reduce sympathetic activity in SHR, thereby resensitizing the depressed beta-adrenoceptor-adenylyl cyclase system.

Treatment in hypertensive cardiac hypertrophy, II. Postreceptor events

We investigated the effect of pharmacological treatment with captopril, nitrendipine, and captopril plus nitrendipine on myocardial heterologous adenylyl cyclase desensitization and the underlying postreceptor defects in spontaneously hypertensive rats (SHR). In myocardial membranes from SHR, stimulation of adenylyl cyclase with guanylylimido-diphosphate (P < .001) and forskolin (P < .05) was significantly reduced, whereas no difference with forskolin was obtained in the presence of manganese chloride. Reconstitution of Gs alpha into Gs alpha-deficient S49 cyc- mouse lymphoma cells revealed no difference between SHR and control rats. In contrast, pertussis toxin labeling of Gi alpha was significantly increased in SHR. The reduction of adenylyl cyclase in SHR was abolished after pertussis toxin treatment of membranes. Treatment with captopril, nitrendipine, or both reduced Gi alpha and increased guanylylimidodiphosphate-stimulated adenylyl cyclase activity in SHR. In summary, heterologous adenylyl cyclase desensitization due to an increase of Gi alpha but in the presence of an unchanged activity of Gs alpha or the catalyst occurs in SHR. This alteration, which could contribute to the progression of contractile dysfunction by producing adrenergic subsensitivity, is sensitive to pharmacological treatment most likely because of a reduction of sympathetic activity.

Effects of enalapril and nitrendipine on the excretion of epidermal growth factor and albumin in hypertensive NIDDM patients

OBJECTIVE

To compare the effect of the antihypertensive drugs nitrendipine and enalapril on the excretion of epidermal growth factor (EGF) and albumin in hypertensive non-insulin-dependent diabetes mellitus (NIDDM) subjects.

RESEARCH DESIGN AND METHODS

After a 4-week washout period, mildly hypertensive (systolic blood pressure [sBP] > or = 140 mmHg and/or diastolic blood pressure [dBP] > or = 90 mmHg) NIDDM patients with albuminuria (15-200 micrograms/min) were randomized into an 8-month-long therapy with either nitrendipine (n = 11) or enalapril (n = 10). Blood pressure, EGF, and microalbumin excretion were measured at baseline and throughout the treatment period.

RESULTS

A significant fall in sBP was noticed in the enalapril group and in dBP in the nitrendipine group. In the enalapril group, EGF excretion progressively increased from 188 to 214 nmol/mmol creatinine after 6 weeks and to 274 after 8 months of therapy (P = 0.03). There was a significant fall in albumin excretion while patients were on enalapril, but in the nitrendipine group, neither albuminuria nor EGF excretion changed significantly. There was no correlation of improved EGF excretion with a decrease in albuminuria or BP.

CONCLUSIONS

The angiotensin-converting enzyme inhibitor enalapril has been effective in decreasing albumin and increasing EGF excretion. Measurement of urinary EGF may provide a new valuable index of renal function.

Nitrendipine and mefruside in elderly hypertensives: effects on blood pressure, cardiac output, cerebral blood flow and metabolic parameters

In this multicentre, randomised, double-blind, cross-over study, we evaluated and compared the effects of nitrendipine (a calcium entry blocker of the dihydropyridine group) and mefruside (a diuretic) on BP, cardiac output, cerebral blood flow and metabolic parameters in 22 elderly hypertensives. Eight weeks of treatment with nitrendipine (27.3 mg daily) and mefruside (30.7 mg daily) significantly reduced BP values to almost the same extent. Heart rate, cardiac output (n = 14), cerebral blood flow (n = 20), renin activity and aldosterone remained unchanged during nitrendipine and mefruside treatment. Nitrendipine did not alter any metabolic parameter (electrolytes, lipid values and blood glucose); in patients treated with mefruside serum potassium fell by 0.4 mmol/l (P < 0.001). Minor adverse events were reported in both treatment groups, mostly due to vasodilation. We conclude that both drugs possess potent and comparable haemodynamic and anti-hypertensive properties. They reduce BP by reducing total peripheral vascular resistance with maintained autoregulation of cerebral blood flow. The metabolic disturbances induced by mefruside seem to be less pronounced than that observed with other thiazide diuretics.

Comparative effects of ramipril and nitrendipine on albuminuria in hypertensive patients with non-insulin-dependent diabetes mellitus and impaired renal function

The purpose of this study was to compare the effects of ramipril and nitrendipine on urinary albumin excretion (UAE) in hypertensive patients with non-insulin-dependent diabetes mellitus (NIDDM) and impaired renal function. Forty patients with mild hypertension with NIDDM and persistent albuminuria (> 300 mg/24h) were studied. After a 3-week run-in period on placebo, patients were randomly treated with ramipril 5 mg once daily or nitrendipine 20 mg once daily for 6 months, according to a double-blind design. Blood pressure (BP), UAE, creatinine clearance and glycosilated haemoglobin were evaluated at the end of the placebo period and after 1,3 and 6 months of active treatment. Both ramipril and nitrendipine significantly lowered BP values without affecting glucose homeostasis and renal function. Despite equivalent BP control, only ramipril afforded a significant reduction in UAE, thus suggesting that the antiproteinuric effect of ramipril is at least partially independent of its anti-hypertensive effect.

Renal functional reserve in calcium channel blocker-treated hypertensive recipients of kidney transplant

Renal functional reserve during infusion of an amino acid solution was examined in 12 cyclosporin-treated kidney recipients at 1 (T1) and 8 months (T2) after transplantation. Patients were retrospectively divided into six normotensive (NT) and six hypertensive recipients (HT) maintained on monotherapy with a calcium channel blocker. Baseline glomerular filtration rates (GFR) were similar in NT and HT at T1 and T2. Renal functional reserve was identical in NT and HT at T1 (15 +/- 7 vs 18 +/- 13 ml/min/1.73 m2) but significantly greater in HT at T2 (11 +/- 5 vs 23 +/- 10 ml/min/1.73 m2; P < 0.05). At T2, baseline proximal tubule outflow (lithium clearance) was greater in HT (26 +/- 8 vs 16 +/- 3 ml/min/1.73 m2; P < 0.05), whereas fractional proximal reabsorption was less (54 +/- 11% vs 67 +/- 5%; P < 0.05). These results indicate that: (i) hypertensive recipients on calcium channel blocker therapy do not exhibit permanent glomerular hyperfiltration until 8 months after transplantation, and have a reduced proximal reabsorption; (ii) measurement of amino acid-stimulated GFR and renal functional reserve is a more sensitive method than that of baseline GFR for evaluating renal function and the effects of therapy in kidney recipients.

[Comparative effects of calcium channel blockers and L-arginine on chronic intermittent hypoxic pulmonary hypertension in rats]

Experiments were carried on rats to study the preventive effects of calcium channel blockers Nitrendipine, Nifedipine and L-Arginine (L- Arginine is the physiological precursor of nitric oxide in endothelium-dependent relaxation) on chronic intermittent hypoxia induced pulmonary hypertension, on the right ventricular hypertrophy and pulmonary vascular pathologic changes. The results showed (1) Nitrendipine, Nifedipine and L-arginine played significant role in preventing chronic hypoxic pulmonary hypertension and the right ventricular hypertrophy. (2) There was no significant difference between Nitrendipine, Nifedipine and L- arginine in preventing hypoxic pulmonary hypertension (P > 0.05). (3) Nitrendipine was better than Nifedipine in reducing the hypoxic pulmonary hypertension.

Cardiac hypertrophy, aortic compliance, peripheral resistance, and wave reflection in end-stage renal disease. Comparative effects of ACE inhibition and calcium channel blockade

BACKGROUND

We wished to assess the respective roles of the antihypertensive and blood pressure (BP)-independent effects of antihypertensive drugs on arterial hemodynamics and left ventricular hypertrophy (LVH) in end-stage renal disease (ESRD) patients.

METHODS AND RESULTS

In a double-blind study, 24 ESRD patients with LVH were randomized to 12 months' administration of either the angiotensin-converting enzyme (ACE) inhibitor perindopril (n = 14) or the calcium channel blocker nitrendipine (n = 10). Repeated measurements of the following parameters were performed: BP (mercury sphygmomanometry), left ventricular mass (LVM, echocardiography), cardiac output (aortic cross-section and velocity integral), total peripheral resistance (cardiac output and mean BP), aortic and large-artery compliance (pulse wave velocity, Doppler flowmeter), and arterial wave reflections (augmentation index, applanation tonometry). Radioimmunoassay was used to determine plasma renin activity, aldosterone, and plasma catecholamine levels. Two-way (time-treatment) ANOVA for repeated measures was used for statistical analysis. Perindopril and nitrendipine induced significant and similar decreases in BP, total peripheral resistance (P < .001), aortic and arterial pulse wave velocities (P < .001), and arterial wave reflections (P < .01). At baseline, the two groups had LVH mostly due to increased LV end-diastolic diameter (LVEDD) (perindopril, 54.3 +/- 1.4 and nitrendipine, 54.3 +/ 2.4 mm) with near-normal mean LV wall thickness (perindopril, 11.4 +/- 0.3 and nitrendipine, 11.2 +/- 0.4 mm). A decrease in LVM was observed only in patients receiving perindopril (from 317 +/- 18 to 247 +/- 21 g) (time-treatment interaction, P = .036). Nitrendipine had no significant effect on LVM (314 +/- 29 versus 286 +/- 32 g). The decrease in LVM observed with perindopril was associated with a reduction in LVEDD (49.9 +/- 1.6 versus 54.3 +/- 1.4 mm after 12 months) (time-treatment interaction, P = .04), while the mean LV wall thickness was unchanged (11.4 +/- 0.3 versus 10.5 +/- 0.5 mm). Cardiac alterations were not correlated with changes in BP or with alterations in plasma renin activity or aldosterone or catecholamine levels.

CONCLUSIONS

In ESRD patients with LVH, ACE inhibition decreases LVM independently of its antihypertensive effect and of associated alterations in arterial hemodynamics. The decrease in LVM was due primarily to a decrease in LV volume, which may have resulted in these patients from chronic volume overload.

Dissociation between antiproteinuric and antihypertensive effect of angiotensin converting enzyme inhibitors in rats

To clarify whether angiotensin converting enzyme (ACE) inhibitors prevent progressive renal injury directly by their antihypertensive effect we administered the ACE inhibitor lisinopril to male MWF/Ztm rats as a single daily dose that lowered blood pressure for only 9 of 24 h. We investigated the effects of this treatment in short- and long-term studies and compared them with another antihypertensive drug, the calcium channel blocker nitrendipine, given to partially control blood pressure as done with the ACE inhibitor. In untreated animals systemic hypertension, proteinuria, and glomerulosclerosis developed spontaneously with age, and lisinopril reduced systemic hypertension and prevented proteinuria and glomerular lesions. Nitrendipine, despite similar blood pressure control, was ineffective in preventing both proteinuria and glomerulosclerosis. After 2 mo of treatment glomerular capillary pressure was significantly reduced by lisinopril and slightly but significantly increased by nitrendipine, compared with untreated controls. The ultrafiltration coefficient was significantly higher in lisinopril than in controls and not significantly changed by nitrendipine. With both drugs, however, glomerular hemodynamic effects were observed only at a few hours after administration and were abolished before the next administration. No significant changes in glomerular tuft volume were observed in treated and untreated animals after 2 and 6 mo of observation. Thus ACE inhibitor, despite only partial control of systemic blood pressure, effectively prevented proteinuria and glomerular injury. Comparable blood pressure control obtained with a calcium channel blocker was not associated with renal protection. These results suggest that ACE inhibitors could protect glomerular microcirculation by a mechanism that is not directly related to their antihypertensive action.

Long-term treatment with either enalapril or nitrendipine stabilizes albuminuria and increases glomerular filtration rate in non-insulin-dependent diabetic patients

The effect of short- (98 days) and long-term (1 year) treatment with nitrendipine (10 to 40 mg/d) and enalapril (5 to 20 mg/d) on kidney function was studied prospectively in a parallel group design in 16 microalbuminuric non-insulin-dependent diabetic patients with mild hypertension and biopsy-proven diabetic glomerulopathy. At the end of the short-term treatment period diastolic blood pressure significantly decreased from 95.4 +/- 2.5 mm Hg to 83.5 +/- 3.5 mm Hg (P < 0.001) in the nitrendipine group and from 96.7 +/- 2.5 to 86.7 +/- 5.6 mm Hg (P < 0.001) in the enalapril group. Both overnight urinary albumin excretion rate and albumin fractional clearance tended to increase in the nitrendipine group and to decrease in the enalapril group, whereas the glomerular filtration rate and the renal plasma flow were similar to baseline in both study groups. At the end of the long-term treatment period diastolic blood pressure significantly decreased from 95.4 +/- 2.5 mm Hg to 86.0 +/- 6 mm Hg (P < 0.005) in the nitrendipine group and from 96.7 +/- 2.1 to 90.8 +/- 4.3 mm Hg (P < 0.05) in the enalapril group. Overnight urinary albumin excretion and albumin fractional clearance were similar to baseline in both study groups. The glomerular filtration rate significantly increased from 70.2 +/- 14.2 to 96.8 +/- 20.4 (P < 0.05) in the nitrendipine group and from 58.9 +/- 10.7 to 78.5 +/- 11.0 (P < 0.05) in the enalapril group. The renal plasma flow also significantly increased from 456.6 +/- 165.3 to 597.2 +/- 178.9 (P < 0.01) in the nitrendipine group.(ABSTRACT TRUNCATED AT 250 WORDS)

Nitrendipine and superoxide dismutase in ischemic renal injury

The effect of the Ca entry blocker nitrendipine, the antioxidant superoxide dismutase (SOD), and a combination of nitrendipine and superoxide dismutase on postischemic renal function was studied in four groups (n = 24) of rats. The rats in group 1 (n = 6) were the ischemic control and received 10 mL of 0.9% NaCl. Group II (n = 6) received SOD 7.0 mg/kg. Group III (n = 6) received nitrendipine 1 mg/kg. Group IV (n = 6) received nitrendipine 1 mg/kg and SOD 7 mg/kg. After administration, both kidneys were rendered ischemic by cross-clamping the renal vessels for 60 min. Comparison of 24-h creatinine clearance (CCr) for 3 days after reversal of ischemia revealed: (a) nitrendipine alone was the most effective in preserving renal function (p < .05); (b) SOD provided some degree of improvement, but only on day 3 (p < .05); (c) a similar result was detected using a combination of nitrendipine and SOD (p < .05); (d) there was no significant difference between SOD and nitrendipine nor between SOD and the combination of nitrendipine/SOD; (e) there was a significant improvement with nitrendipine when compared to the combination of nitrendipine/SOD (p < .05).

Comparative effects of monatepil, a novel calcium antagonist with alpha 1-adrenergic-blocking activity, and nitrendipine on lipoprotein and carbohydrate metabolism in patients with hypertension

The effects of monatepil, a new calcium antagonist with alpha 1-blocking activity, and nitrendipine on lipoprotein and carbohydrate metabolism in 86 patients with mild-to-moderate hypertension were examined in a randomized, open-label, multicenter (32 hospitals) study. Thirty-nine patients treated with monatepil and 33 patients treated with nitrendipine completed the 12-week study. Monatepil and nitrendipine each significantly decreased both systolic and diastolic blood pressure. Changes in heart rate were not seen in either group. Monatepil administration significantly decreased total cholesterol, low density lipoprotein (LDL) cholesterol, the LDL cholesterol to high density lipoprotein (HDL) cholesterol ratio, apolipoprotein (Apo) B levels, and HbA1c levels, whereas no changes in these measurements were observed in nitrendipine-treated patients. Monatepil also significantly decreased lipoprotein(a) levels, but there were no significant changes in HDL cholesterol, Apo-AI, or Apo-E levels. After nitrendipine treatment, the C peptide concentration decreased significantly, although no significant changes were observed in fasting blood glucose or immunoreactive insulin levels. On the basis of these results, it can be concluded that monatepil belongs to a new class of antihypertensive calcium antagonist with favorable carbohydrate metabolism and lipid-lowering activity, although the clinical importance of these findings has not been established.

Changes in plasma norepinephrine concentration and thrombocyte alpha 2-adrenoceptor density during long-term antihypertensive therapy with nitrendipine and captopril

Antihypertensive drugs influence the sympathetic nervous system in different ways that may cause adverse or beneficial effects. We treated 48 hypertensive patients with either nitrendipine (10-20 mg twice daily, b.i.d.) or captopril (25-50 mg b.i.d.) for 16 weeks to evaluate changes in plasma catecholamines, platelet alpha 2- and lymphocyte beta 2-adrenoceptors. Blood pressure (BP) decreased from 153/95 to 135/87 mm Hg with captopril and from 155/99 to 137/89 mm Hg with nitrendipine. Treatment with nitrendipine significantly stimulated plasma norepinephrine (NE) from 327 +/- 37 to 446 +/- 50 pg/ml, and treatment with captopril resulted in a significant reduction in platelet alpha 2-adrenoceptor density from 265 +/- 39 to 171 +/- 26 fmol/mg protein. Despite having equal BP-lowering properties, captopril and nitrendipine have different effects on the sympathetic nervous system. Stimulation of plasma NE during long-term treatment with nitrendipine may contribute to possible adverse effects, whereas reduction in alpha 2-adrenoceptors induced by captopril may contribute to the vasodilating effect of angiotensin-converting enzyme (ACE) inhibition.

Influence of coenzyme Q-10 on the hypotensive effects of enalapril and nitrendipine in spontaneously hypertensive rats

Administration of coenzyme Q-10 (10 mg/kg) once a day for 4 weeks decreased the arterial blood pressure in SHR's. Enalapril and nitrendipine administered in a single dose caused significant decrease of blood pressure. Application of enalapril and nitrendipine to rats chronically pretreated with coenzyme Q-10 revealed, that the maximal hypotensive effect was not greater, but it lasted much (ca. 2-times) longer. Independently of mechanism of this interaction it may be suggested that the chronic administration of coenzyme Q-10 would create the possibility of significant decrease of the frequency of some antihypertensive drug administration.

[Does long-term blood pressure reduction in patients with essential hypertension improve concomitant metabolic disorders?]

AIM

Aim of this study was to investigate the occurrence of metabolic abnormalities in patients with newly diagnosed essential hypertension and to assess the effects of a blood pressure lowering drug therapy on the respective variables.

PATIENTS AND RESULTS

Twenty-six hypertensive subjects (12 female, 14 male) were included in the study. Twenty-one normotensive subjects (9 female, 12 male) served as a control group. During an oral glucose tolerance test the hypertensive subjects had higher blood glucose and serum insulin levels than the controls. The hypertensive patients also showed higher triglyceride concentrations and a more abdominal pattern of body fat distribution. In addition, the women with essential hypertension exhibited a higher free androgen index (32.2 +/- 14.8 vs 20.1 +/- 15.0%, p < 0.05) than the women of the control group. After a 3 to 6 month treatment period with nifedipine or nitrendipine the elevated blood pressure of the hypertensives was significantly reduced. In a second glucose tolerance test carried out in 13 patients blood glucose, serum insulin and triglyceride concentrations were significantly lower compared to the pretreatment period. The other metabolic and hormonal variables remained unchanged.

CONCLUSION

This observation raises the question, whether a long-term vasodilatating antihypertensive therapy can improve the metabolic abnormalities found in patients with essential hypertension.

[Concentration of free intracellular magnesium in the myocardium of spontaneously hypertensive rats treated chronically with calcium antagonist or angiotensin converting enzyme inhibitor]

In this study, we determined a) whether chronic antihypertensive treatment could alter myocardial free intracellular magnesium concentrations, b) whether changes in magnesium concentration would correlate with resistance to anoxia of hypertensive rat hearts. Six-month old male spontaneously hypertensive (HT) rats (n = 11) were compared to rats from the same strain treated with a calcium channel antagonist, nitrendipine (60 mg/kg/j; n = 11) or with a converting-enzyme inhibitor, perindopril (2 mg/kg/j; n = 9) during three months. The hearts were perfused in retrograde isovolumic mode and submitted to a standardized anoxia-recovery protocol. Aortic perfusion pressure and left ventricular pressure were constantly monitored. P-31 NMR spectra were simultaneously recorded and allowed to quantify the changes in myocardial inorganic phosphate, phosphocreatine and ATP. The pH was derived from the chemical shifts of inorganic phosphate and phosphocreatine, and the free intracellular magnesium concentration from the alpha-beta chemical shifts of ATP. Both treatments lowered systolic blood pressure and reversed left ventricular hypertrophy, perindopril being slightly more efficient at the dose administered. Intracellular magnesium concentration, calculated from the P-31 NMR spectra, was 277 +/- 17 microM in the untreated hypertensive group, 311 +/- 15 microM in the nitrendipine group and 401 +/- 17 microM in the perindopril group (p < 0.001 versus untreated and nitrendipine). There was a significant correlation between intracellular magnesium concentration and left ventricular developed pressure at the early stage of post-anoxic recovery (r = 0.61; p < 0.01). P-31 NMR spectroscopy demonstrates an increase in myocardial free intracellular magnesium concentration following chronic administration of an angiotensin-converting enzyme inhibitor, perindopril, spontaneously hypertensive rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Erythrocyte Na+,K(+)-ATPase activity does not predict therapeutic response to calcium antagonists in essential hypertension

We investigated whether pre- and posttreatment analysis of erythrocyte membrane Na+,K(+)-ATPase (EC 3.6.1.37) activity would be a useful marker for screening hypertensive patients to determine who might benefit from treatment with calcium antagonists. Erythrocyte Na+,K(+)-ATPase activity and sodium and potassium (ENa, EK) contents were determined in controls and in patients with untreated essential hypertension before and after 4 weeks of treatment with nitrendipine. Na+,K(+)-ATPase activity was significantly (P < 0.0001) less in untreated hypertensive patients (n = 15; 104.60 +/- 29.37 nmol of phosphate produced per milligram of protein per hour) than in controls (n = 15, 171.87 +/- 34.42). After 4 weeks of nitrendipine treatment Na+,K(+)-ATPase activity was greater than in the pretreatment group: 158.13 +/- 26.80 (P < 0.001). Pretreatment ENa contents (22.34 +/- 4.77 mmol/L) were significantly (P < 0.0001) higher than in the normotensive group (13.14 +/- 3.32 mmol/L), but there was no significant difference between the controls and the posttreatment group (14.84 +/- 3.49 mmol/L). The control and pretreatment groups showed negative correlations between enzyme activity and systolic/diastolic blood pressure (P < 0.0001). The control and the posttreatment groups showed an inverse correlation between enzyme activity and ENa contents: r = -0.608 (P < 0.05) and r = -0.724 (P < 0.001), respectively. Although Na+,K(+)-ATPase is restored in hypertensive patients receiving nitrendipine treatment, relative changes in enzyme activity in relation to relative reduction in blood pressure response to treatment were not correlated.