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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Antihypertensive effects of a novel calcium antagonist, MPC-1304, (+-)-methyl 2-oxopropyl 1,4-dihydro-2,6-dimethyl-4-(2-nitrophenyl)-3,5- pyridine-dicarboxylate and its active metabolites were investigated in experimental hypertensive rats and dogs and compared with those of other dihydropyridine derivatives (nifedipine, nisoldipine, nicardipine, and nitrendipine). MPC-1304 had a dose-related antihypertensive effect with a slight increase in heart rate (HR) in rats. The antihypertensive effects of MPC-1304 were more potent than those of other dihydropyridines, and its active metabolites had antihypertensive effects comparable to those of other dihydropyridines. The hypotensive effects of MPC-1304 were stronger in hypertensive rats than in normotensive rats. During repeated oral administration of MPC-1304 to spontaneously hypertensive rats (SHR, once daily for 4 weeks, 0.3-3 mg/kg), dose-response curves of the antihypertensive effect did not change and body weight gain was equal to that of the vehicle-treated group. When given orally to conscious renal hypertensive dogs, MPC-1304 0.1-0.3 mg/kg had a potency and duration of antihypertensive action comparable to that of nitrendipine (1-3 mg/kg). MPC-1304 increased coronary blood flow (CBF) and aortic blood flow (ABF) in conscious normotensive dogs. In conclusion, MPC-1304 and its active metabolites have potent antihypertensive effects and cause slight tachycardia, and they may be useful in treating hypertension.
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PMID:Antihypertensive effects of MPC-1304, a novel calcium antagonist, in experimental hypertensive rats and dogs. 128 Jul 33

Vascular reactivity and systolic blood pressure (SBP) were studied in tail artery rings isolated from stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive, Wistar-Kyoto rats (WKY). After a control week on a diet with 1% of calcium, the animals were randomly assigned to three groups, which were fed with 1% (control), 0.4% (low) or 2.5% (high) dietary calcium. Both vascular reactivity and SBP were studied in the same animal during 9 weeks after changing diets. In the SHRSP rats on high Ca diet, maximal contractile responses to norepinephrine and serotonin (10(-10) to 10(-4) M) and to KCl (5 to 105 mM) were markedly decreased at the end of the study with respect to the control diet. These vascular changes were accompanied by a decrease of SBP in the same animals. Low calcium diet prevented the age-related increase of SBP in SHRSP rats and produced vascular changes of a lesser magnitude. WKY rats showed no significant modifications of SBP or vascular reactivity. Since plasmatic Ca2+ levels were not altered, the changes detected could not be attributed to a direct depressant effect of high calcium on the vascular smooth muscle cell (i.e. a "stabilizing action" of calcium). It is speculated that high dietary calcium could modulate the synthesis of calcium binding proteins of the plasma membrane, decreasing vascular reactivity and the elevated vascular resistance which is usually present in hypertension.
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PMID:Dietary calcium on vascular reactivity in normotensive and spontaneously hypertensive rats. 128 92

We wished to clarify the effects of a newly developed calcium antagonist, manidipine hydrochloride (HCl), on renal microcirculation in hypertensive rats by using the micropuncture technique. Oral administration of manidipine HCl for 2 months reduced systemic blood pressure (BP), did not change the single-nephron glomerular filtration rate (SNGFR), but increased the SNG plasma flow (SNGPF). Moreover, the glomerular transcapillary hydraulic pressure difference (delta P), which is assumed to be the parameter most related to development of glomerulosclerosis, was significantly reduced. Both afferent and efferent arteriolar resistance (RA and RE) were reduced. Intravenous (i.v.) infusion of manidipine HCl (20 micrograms/kg) decreased systemic BP but did not change SNGFR, SNGPF, or delta P. Both RA and RE were also significantly decreased. These results indicate that chronic administration of manidipine HCl increases renal blood flow (RBF) by dilating the afferent arterioles and improves glomerular hypertension by dilating the efferent arterioles. Thus, manidipine HCl might be a beneficial antihypertensive agent for patients with renal diseases. Because acute i.v. infusion of manidipine HCl did not change delta P, apparently time must elapse before glomerular hypertension is corrected.
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PMID:Effects of manidipine hydrochloride on the renal microcirculation in spontaneously hypertensive rats. 128 91

Nilvadipine is absorbed rapidly and completely and its absolute bioavailability is about 14-19% because of its high first-pass metabolism. Maximum plasma levels and the extent of bioavailability increase proportionally with the dose. Nilvadipine is mainly excreted via the kidney as inactive metabolites. Slow tissue redistribution is probably the reason for the terminal elimination half-life of 15-20 h. There was a good correlation between the estimated tissue concentration and the reduction in blood pressure in patients. The use of the sustained-release pellet formulation can prevent plasma level peaks and thereby lessen the typical side effects of dihydropyridine calcium antagonists. The pharmacokinetics of nilvadipine were not affected by impaired renal function, and although the bioavailability was increased in liver cirrhosis, there was no accumulation after repeated doses. There was no effect on plasma digoxin levels. The plasma concentration of nilvadipine can be affected by either activation or inhibition of the cytochrome P450 system. The use of a sustained-release once-a-day formulation to lower the peaks in plasma levels along with nilvadipine's long terminal half-life means that this well-tolerated pharmaceutical formulation can be employed in clinical trials for the treatment of hypertension and expected to work over 24 h.
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PMID:Pharmacokinetics of nilvadipine. 128 85

In an open monocentric phase II study, 20 inpatients with hypertension were treated with a single daily dose of nilvadipine for 3 weeks after a 1-week placebo washout phase. The initial dose in all patients was 8 mg/day p.o.; this was doubled to 16 mg once daily if an adequate blood pressure reduction was not achieved after 10 days on 8 mg. The objective of the study was to investigate the effect of this new calcium antagonist on the blood pressure in hypertensive patients. This was done by means of a 24-h blood pressure profile (with measurements at 0.5, 1, 2, 4, 8, 12, and 24 h after administration), and over the complete course of the treatment period (blood pressure measurements each day just before the medication was given). In addition, by determination of the nilvadipine plasma levels on the first, tenth, and last medication day, a possible concentration-efficacy relationship was to be ascertained between plasma concentration of nilvadipine and the observed blood pressure-lowering effect of the drug. Adequate blood pressure reductions were achieved with nilvadipine 8 mg once daily in 13 patients; 7 required a doubling of the dosage to 16 mg/day. Already on the first day of therapy, both the systolic and diastolic blood pressures were significantly reduced compared to those in the placebo phase (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:24-hour blood pressure control after single daily doses of nivaldipine in patients with essential hypertension. 128 87

Calcium antagonists are of particular importance in the treatment of hypertension because they influence the free cytoplasmic calcium concentration and thereby many pressor mechanisms in the smooth muscle cell. A fall in the peripheral resistance is the main hemodynamic effect, and this is more marked with the second-generation calcium antagonists because they are more vasoselective than the first calcium-channel blockers. Particularly important is their lack of effect on lipid and glucose metabolism, as well as the absence of serious side effects. It has not yet been possible to confirm that the antiatherogenic effect found in some animal models also occurs in humans. Calcium antagonists are effective, safe, and well-tolerated antihypertensive agents that can be combined with all other antihypertensives with the exception of the combination of verapamil and a beta-blocker. They are easy to dose for individualized "stepped" therapy. They have a particular role in hypertensive patients with cardiac effects secondary to hypertension, coronary artery disease, obstructive bronchial diseases, diabetes, renal disease, and peripheral arterial occlusive disease.
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PMID:The role of calcium antagonists in the treatment of hypertension. 128 89

One of the earliest structural changes in the heart adapting to hypertension is left ventricular hypertrophy, which can now be exactly measured by echocardiography. Left ventricular hypertrophy increases the incidence of coronary artery disease, heart failure, and sudden death severalfold, independent of the blood pressure levels. Left ventricular hypertrophy requires specific antihypertensive therapy that controls both high blood pressure and increased left ventricular mass. Preliminary data from clinical studies indicate that regression of left ventricular hypertrophy leads to a better cardiovascular prognosis. Sympatholytic substances, angiotensin-converting enzyme (ACE) inhibitors, and calcium antagonists are antihypertensive agents that effected adequate reductions in blood pressure as well as regression of left ventricular hypertrophy.
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PMID:Hypertensive heart disease--significance of left ventricular hypertrophy. 128 90

The course and prognosis of chronic renal failure are much worse in hypertensive patients than in normotensive patients with otherwise similar basic disease. Therefore, antihypertensive measures with a combination of diuretics, beta-blockers, and vasodilators have clearly been shown to improve the progression of diabetic nephropathy. Treatment of hypertension with angiotensin-converting enzyme (ACE) inhibitors has also been shown to have a favorable effect on the prognosis of chronic renal failure. In the past few years, more knowledge about the pathogenesis of hypertension and the development of hypertension-induced organ damage has been followed by changing attitudes to antihypertensive therapy and the introduction of calcium antagonists for the treatment of hypertension, even in chronic renal failure. ACE inhibitors and calcium antagonists seem to be advantageous in the prognosis of chronic renal failure as they act on the humoral and trophogenic factors now known to be important in antihypertensive therapy.
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PMID:The effect of antihypertensive therapy on the course of renal failure. 128 93

The pharmacokinetics and pharmacodynamics of nilvadipine, a new dihydropyridine calcium antagonist, were examined in 16 patients divided into two different population groups. The first group of eight patients had arterial hypertension with limited renal function (creatinine clearance of 15-50 ml/min). The second group of eight patients had arterial hypertension with no concomitant renal dysfunction (creatinine clearance over 80 ml/min). Following a 1-week placebo washout period, all patients were given 8 mg of nilvadipine once daily for 10 days. The diastolic blood pressure (24-h postdose) fell in group I from a mean of 100.5 to 91.5 mm Hg and in group II from a mean of 106.7 to 88.2 mm Hg, which was significant in comparison to the placebo period. In neither group was there a significant change in heart rate, renin and aldosterone plasma levels, serum electrolytes, or sodium and potassium excretion. The pharmacokinetics of the unchanged nilvadipine were not significantly different between group I and group II. Neither group showed unchanged nilvadipine in urine. There was a slight increase in plasma levels of the inactive main metabolites M3 and M7; there was correspondingly less M3 found in the urine of group I patients. Nilvadipine appears to be an effective hypotensive agent at single daily doses of 8 mg. This dosage was well tolerated. The findings of this study did not suggest that lower doses need to be given to patients with limited renal function, at least not those with a creatinine clearance between 15 and 50 ml/min.
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PMID:Nilvadipine in hypertension with renal dysfunction. 128 94

Pronounced vascular calcium overload, especially of compliance arteries, is an important aspect of aging, and of various age-related vascular diseases such as hypertension and atherosclerosis. The development of new drugs specifically aimed at attenuating the evolution and/or pathological consequences of vascular calcium overload is hindered by the paucity of animal models available. Although several laboratory animals exhibit vascular calcium overload, this evolves slowly and is far less marked than in man. Nevertheless, Fleckenstein and associates (1989) suggested a suitable animal model involving the treatment of young rats with vitamin D3 and nicotine; such treatment produces pronounced vascular calcium overload within a few weeks. This paper describes the cardiovascular effects of such treatment, and our preliminary attempts to pharmacologically modify vascular calcium overload and its cardiovascular consequences.
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PMID:Vascular calcium overload. Physiological and pharmacological consequences. 128 72


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