Dihydropyridine-type Calcium Channel Blocker Research Articles

Mechanisms of plaque stabilization for a charged calcium channel blocker in coronary artery disease.

Coronary artery disease (CAD) results from atherosclerosis, a systemic vascular disorder that is the leading cause of death and disability throughout much of the developed world. Because cellular changes associated with vulnerable atherosclerotic plaque are characterized by a loss of normal calcium regulation, there is strong interest in a potential antiatherosclerotic role for calcium channel blockers. This hypothesis has been supported by investigational studies conducted in well-defined cellular and animal models of atherosclerosis. In addition, several clinical studies have tested the benefit of calcium channel blockers among patients with mild-to-moderate CAD. More recent trials have shown reductions in cardiovascular events after treatment with amlodipine, a long-acting, dihydropyridine-type calcium channel blocker. The Prospective Randomized Evaluation of the Vascular Effects of Norvasc Trial (PREVENT) demonstrated that patients with documented CAD treated with amlodipine experienced marked reductions in cardiovascular events compared with patients receiving placebo. Amlodipine also was associated with significant slowing of carotid atherosclerosis, an important surrogate marker for CAD, independent of blood pressure modification. These results have renewed interest in potential plaque stabilization properties of third-generation calcium channel blockers and their possible therapeutic role in CAD.

NC-1500 prevents concanavalin A-induced mice hepatitis without affecting cytokine gene expression.

NC-1500 is a dihydropyridine type calcium channel blocker. The effect of NC-1500 on mice concanavalin A-induced hepatitis was examined. Treatment of mice with concanavalin A (Con A) caused elevation of plasma transaminase. Pretreatment of mice with NC-1500 (3, 10 and 30 mg/kg, p.o.) prevented this Con A-induced elevation of plasma transaminase. Treatment of mice with Con A induced tumor necrosis factor-alpha (TNF-alpha) mRNA expression in the liver. However, NC-1500 (30 mg/kg, p.o.) did not affect this Con A-induced TNF-alpha mRNA expression in the liver. The present results showed that NC-1500 inhibited Con A-induced hepatitis without affecting TNF-alpha mRNA expression in the liver.

Alcohol‐Induced Reductions in Cardiac Protein Synthesis In Vivo Are Not Ameliorated by Treatment With the Dihydropyridine Calcium Channel Blocker Amlodipine

Various studies have indicated that acute ethanol dosage perturbs cardiac function and/or structure with concomitant reductions in protein synthesis. Cellular calcium homeostasis is also perturbed, which may contribute to altered protein synthesis. This is supported by the observation that calcium channel blockers can prevent numerous features of alcohol-induced pathology. However, many of these studies have been carried out in vitro, employing supraphysiological levels of alcohol, or have failed to address whether their results obtained in isolated systems have direct relevance in vivo. The aim of the present investigation was to examine the response of cardiac protein synthesis in vivo due to a physiologically relevant dose of ethanol and determine whether a calcium channel antagonist could prevent these effects. Changes in cardiac protein synthesis rates in vivo were assessed by measuring the fractional rates of protein synthesis (i.e., ks) using a "flooding dose" of [3H]phenylalanine. Rats were treated either acutely (10 mg/kg body weight, 3 hr) or chronically (10 mg/kg body weight/day, 30 days) with amlodipine, a dihydropyridine-type calcium channel blocker, before dosing with ethanol (75 mmol/kg body weight, 2.5 hr). Ethanol (75 mmol/kg body weight) inhibited cardiac protein synthesis after 1 hr. Similar responses were recorded at 2.5 and 6 hr after ethanol dosage. At 24 hr, ethanol decreased food intakes. However, a direct comparison between pair-fed controls and alcohol-dosed rats also showed a decrease in cardiac protein synthesis after 24 hr. Acute alcohol dosage reduced cardiac protein synthesis in mixed, myofibrillary, and sarcoplasmic protein fractions. Similar results were obtained when data were expressed relative to ribonucleic acid (i.e., kRNA). Neither acute nor chronic treatments with the calcium antagonist amlodipine ameliorated the deleterious actions of ethanol on protein synthesis. Ethanol may affect cardiac protein synthesis independently of altered calcium entry.

Protection against endothelial abnormalities by a novel calcium channel blocker, AE0047, in stroke-prone spontaneously hypertensive rats

We investigated the protective effect of chronic treatment with AE0047, a dihydropyridine-type calcium channel blocker, on vascular endothelial abnormalities in stroke-prone spontaneously hypertensive rats (SHRSP). Ten-week repeated antihypertensive treatment with AE0047 inhibited blood pressure elevation and improved endothelium-dependent relaxation in response to acetylcholine in aorta isolated from SHRSP. Furthermore, the abnormal production of prostaglandin I 2 and thromboxane A 2 in the aorta was normalized to a level equivalent to that in Wistar-Kyoto rats. These results suggest that chronic treatment with AE0047 exerts protective effects against endothelial abnormalities associated with the development of hypertension.

Changes of plasma L-arginine levels in spontaneously hypertensive rats under induced hypotension.

Nicardipine, a dihydropyridine type calcium channel blocker, was infused at two flow-rates into spontaneously hypertensive (SH) and control normotensive Wistar-Kyoto (WKY) rats (young, 6-week-old and adult, 23-week-old, n = 5) under pentobarbital anesthesia, to cause hypotension. Mean arterial blood pressure and the concentrations of plasma amino acids and norepinephrine (NE) were measured before infusion and at each step of the infusion. The reduction in blood pressure caused by nicardipine induced a decrease in plasma L-arginine concentration in both young and adult SH rats, this effect being larger in adult rats. There was no significant change in plasma levels of L-arginine in age-matched WKY rats. The concentration of other amino acids did not change in both rat strains. On the contrary, there was an increase in plasma NE concentration in both SH and WKY rats after infusion with nicardipine. Plasma L-arginine concentration showed a good inverse correlation with the logarithm of plasma NE concentration in SH and WKY rats and the correlation was expressed as Y = -alpha log(X) + m (Y, plasma L-arginine concentration (nmol/mL); X, plasma NE concentration (pmol/mL); alpha, a slope; and m, an intercept). alpha, 43.0 and 4.35 for 23-week-old SH and WKY rats, respectively, and 17.0 and 4.0 for 6-week-old SH and WKY rats, respectively. The present data together with previous data suggest a direct noradrenergic stimulation of the synthesis of nitric oxide (NO) from L-arginine. The findings also indicate an impairment of the L-arginine metabolism or pools in SH rats compared with WKY rats. The deficiency of L-arginine increases with the age of SH rats and could be related to the development and maintenance of hypertension due to inefficient production of NO.

Age-related weakening of baroreflex-mediated sympathetic activity in spontaneously hypertensive rats in response to blood pressure reduction.

Nicardipine, a dihydropyridine type calcium channel blocker, was infused into 4-, 6-, and 23-wk-old spontaneously hypertensive (SH) and age-matched normotensive Wistar-Kyoto (WKY) rats (under sodium thiobutabarbital anesthesia and ventilation, n = 4) through the left femoral vein, resulting in the reduction of blood pressure. In each rat, mean arterial blood pressure, heart rate, and the concentration of plasma catecholamines (CAs), norepinephrine (NE), and epinephrine (E) were concomitantly determined, and the correlations between these three variables were studied. During the infusion of nicardipine, the plasma concentration of CAs was measured with an automatic detection system in blood samples collected from the right femoral artery of each rat. The reduction in blood pressure induced by nicardipine brought about an increase in plasma CA levels. The blood pressure correlated well with the logarithm of plasma NE or E concentration according to the formula Y= -alpha log (X) + m (Y, blood pressure; X, concentration of plasma NE or E; a, slope; and m, intercept). The slopes (as) of 6-wk-old and 23-wk-old SH rats were significantly greater than those of aged-matched WKY rats, meaning that the increment in plasma CAs in response to a decrease in blood pressure was smaller in SH than in WKY rats of similar ages. However, no significant differences were found between the as of 4-wk-old SH and WKY rats. We conclude that the increment in the baroreflex-mediated sympathetic activity in response to a drop in blood pressure induced by nicardipine is similar or greater in prehypertensive SH than in normotensive WKY 4-wk-old rats, while the increment becomes smaller in SH rats with the onset of hypertension (6-wk-old rats), and is much less in fully hypertensive adult (23-wk-old) SH rats than in age-matched WKY rats. On the basis of these findings and previous data obtained by neurography, we conclude that plasma CAs can be used to evaluate baroreflex-mediated sympathetic activity countering the blood pressure reduction caused by calcium antagonists.

Nimodipine, a dihydropyridine-type calcium channel blocker, prevents alcoholic hepatitis caused by chronic intragastric ethanol exposure in the rat

It has been shown recently that inactivation of Kupffer cells prevents free radical formation and early alcohol-induced liver injury, and that hypoxia subsequent to a hypermetabolic state caused by activated Kupffer cells is likely involved in the mechanism. Calcium is essential for the activation of Kupffer cells, which contain L-type voltage-dependent Ca2+ channels. Therefore, the purpose of this study was to determine whether a Ca2+ channel blocker, nimodipine, prevents early alcohol-induced liver injury in vivo and to evaluate its effect on intracellular calcium ([Ca2+]i) in Kupffer cells in vitro. Male Wistar rats were exposed to ethanol (10-12 g/kg/d) continuously for up to 4 weeks via intragastric feeding using an enteral model developed by Tsukamoto and French. In this model, ethanol causes steatosis, necrosis, and inflammation in only a few weeks. In the experimental group, nimodipine (10 mg/kg/d) was added to the diet and was shielded from direct light. Nimodipine had no effect on body weight over a 4-week treatment period, nor were mean ethanol concentrations or their cyclic pattern in urine affected. The mean urine ethanol values were 154 +/- 11 mg/dL in ethanol-fed and 144 +/- 38 mg/dL in ethanol + nimodipine-fed rats. After 4 weeks, serum aspartate transaminase (AST) levels were elevated in ethanol-treated rats to 183 +/- 78 U/L. In contrast, values only reached 101 +/- 9 U/L in rats given nimodipine + ethanol-values which were significantly lower. Steatosis and necrosis assessed histologically were also reduced significantly by nimodipine. Nimodipine (10 micrograms/kg) also blocked the swift increase in alcohol metabolism and elevated oxygen consumption in perfused livers from rats treated with alcohol in vivo. Further, in cultured Kupffer cells, nimodipine (1 mumol/L) largely prevented the elevation in [Ca2+]i caused by lipopolysaccharide (LPS) (LPS, 200 +/- 11 nmol/L; LPS + nimodipine, 94 +/- 31 nmol/L; P < .05). These results indicate that nimodipine prevents alcoholic hepatitis, possibly by inhibition of endotoxin-mediated Kupffer cell activation.

Nimodipine, a dihydropyridine-type calcium channel blocker, prevents alcoholic hepatitis caused by chronic intragastric ethanol exposure in the rat

It has been shown recently that inactivation of Kupffer cells prevents free radical formation and early alcohol-induced liver injury, and that hypoxia subsequent to a hypermetabolic state caused by activated Kupffer cells is likely involved in the mechanism. Calcium is essential for the activation of Kupffer cells, which contain L-type voltage-dependent Ca2+ channels. Therefore, the purpose of this study was to determine whether a Ca2+ channel blocker, nimodipine, prevents early alcohol-induced liver injury in vivo and to evaluate its effect on intracellular calcium ([Ca2+]i) in Kupffer cells in vitro. Male Wistar rats were exposed to ethanol (10-12 g/kg/d) continuously for up to 4 weeks via intragastric feeding using an enteral model developed by Tsukamoto and French. In this model, ethanol causes steatosis, necrosis, and inflammation in only a few weeks. In the experimental group, nimodipine (10 mg/kg/d) was added to the diet and was shielded from direct light. Nimodipine had no effect on body weight over a 4-week treatment period, nor were mean ethanol concentrations or their cyclic pattern in urine affected. The mean urine ethanol values were 154 +/- 11 mg/dL in ethanol-fed and 144 +/- 38 mg/dL in ethanol + nimodipine-fed rats. After 4 weeks, serum aspartate transaminase (AST) levels were elevated in ethanol-treated rats to 183 +/- 78 U/L. In contrast, values only reached 101 +/- 9 U/L in rats given nimodipine + ethanol-values which were significantly lower. Steatosis and necrosis assessed histologically were also reduced significantly by nimodipine. Nimodipine (10 micrograms/kg) also blocked the swift increase in alcohol metabolism and elevated oxygen consumption in perfused livers from rats treated with alcohol in vivo. Further, in cultured Kupffer cells, nimodipine (1 mumol/L) largely prevented the elevation in [Ca2+]i caused by lipopolysaccharide (LPS) (LPS, 200 +/- 11 nmol/L; LPS + nimodipine, 94 +/- 31 nmol/L; P < .05). These results indicate that nimodipine prevents alcoholic hepatitis, possibly by inhibition of endotoxin-mediated Kupffer cell activation. (Hepatology 1996 Aug;24(2):391-7)

Nimodipine, a dihydropyridine-type calcium channel blocker, prevents alcoholic hepatitis due to chronic intragastric ethanol exposure in the rat

Nimodipine, a dihydropyridine-type calcium channel blocker, prevents alcoholic hepatitis due to chronic intragastric ethanol exposure in the rat

Renoprotective effect of enalapril in uninephrectomized spontaneously hypertensive rats with neonatal streptozotocin-induced diabetes

We compared the renoprotective effect between angiotensin-converting enzyme inhibitor, enalapril, and a dihydropyridine-type calcium channel blocker, nicardipine, in a severe form of renal injury in rats. Two-day-old spontaneously hypertensive rats (SHR) were injected with streptozotocin or vehicle as control. UNX was performed at 3 weeks of age, and enalapril or nicardipine was administered in drinking water from 7 weeks of age. Uninephrectomy (UNX) markedly exacerbated hypertension and renal injury in the nondiabetic and diabetic SHR. Enalapril and nicardipine comparably reduced blood pressure in UNX diabetic SHR. However, serum creatinine was significantly elevated in the nicardipine-treated group as compared with the enalapril-treated group at 24 weeks of age (nicardipine-treated group, 67 ± 4 μM; enalapril-treated group, 49 ± 3 μM; P < 0.01; untreated group 57 ± 4 μM). Furthermore, the incidence of glomerular sclerosis was similar between untreated and nicardipine-treated groups, whereas it tended to be reduced in the enalapril-treated group. In a separate experiment of diabetic SHR without UNX, enalapril therapy significantly ameliorated hyperglycemia and albuminuria ( P < 0.01). This study showed that a renoprotective effect was seen in enalapril but not in nicardipine in UNX diabetic SHR despite the comparable reduction of blood pressure. This suggests that enalapril may be more effective than nicardipine in delaying the progression of a severe form of diabetic nephropathy.

P3-108 - Protection of endothelial dysfunction by AE0047, a dihydropyridine-type calcium channel blocker, in stroke-prone spontaneously hypertensive rats.

P3-108 - Protection of endothelial dysfunction by AE0047, a dihydropyridine-type calcium channel blocker, in stroke-prone spontaneously hypertensive rats.

Effect of long term treatment with the dihydropyridine-type calcium channel blocker darodipine (PY 108-068) on the cerebral capillary network in aged rats

The effects of treatment with the dihydropyridine Ca +2 antagonist darodipine (PY 108-068) on age-related changes in the cerebral capillary network was studied using alkaline phosphatase histochemistry with quantitative image analysis. The investigation was performed on male Wistar rats of 12 months (adult reference group) and 27 months. The 27-month-old rats consisted of two groups, the first of control untreated animals and the second of rats receiving an oral dose of 5 mg/kg/day of darodipine from the 21st to the 27th month. The cerebral areas examined included the frontal cortex, the occipital cortex, Ammon's horn of the hippocampus, and the dentate gyrus. The number and the average length of alkaline phosphatase-positive capillaries were decreased in old rats, when compared with adult rats. The intercapillary distance, which is considered as a sensitive parameter for capillary density was increased in aged rats in comparison to adult rats. The capillary diameter was increased slightly or unchanged in old rats. The Ammon's horn and the frontal cortex were the cerebral areas most affected by age-dependent changes of the capillary network. Treatment with darodipine increased the number and the average length of alkaline phosphatase-reactive capillaries and reduced the intercapillary distance and the diameter of cerebral capillaries in old rats. The pericapillary microvenvironment of the Ammon's horn was the most sensitive to treatment with darodipine. The above results showed that treatment with darodipine is capable of counteracting some microvascular changes occurring in the brain of aged rats. This suggests that the blockade of dihydropyridine-type Ca 2+ channels has a positive effect on the brain microvascular system and may counteract the impairment of pericapillary microenvironment occurring with aging.

Nicardipine may impair glucose metabolism in hypertensive diabetic patients

The respective effects of 6 month's administration of β-blockers (atenolol, metoprolol, carteolol and arotinolol), calcium-channel blockers (nicardipine, diltiazem) and angiotensin converting enzyme inhibitor (enalapril) on hemoglobin A lc (HbA lc) levels were evaluated in hypertensive patients with non-insulin-dependent diabetes mellitus (NIDDM), using a retrospective method. NIDDM patients with stable HbA lc and body weight were selected for this study. The following results were obtained. (1) The administration of nicardipine or β-blockers significantly elevated HbA lc levels. (2) The administration of diltiazem or enalapril did not have any influence on HbA lc levels. These findings suggest that not only β-blocker but nicardipine (dihydropyridine type calcium-channel blocker) may cause deterioration in glucose metabolism in NIDDM patients.

Effect of short-term ethanol treatment on voltage-dependent calcium channels in Kupffer cells

Kupffer cells, the resident hepatic macrophages, are activated by calcium, and several reports indicate that their function (e.g., phagocytosis and cytokine production) is altered by ethanol. We recently found that Kupffer cells contain L-type voltage-dependent Ca2+ channels. The purpose of this study, therefore, was to evaluate the effect of short-term ethanol treatment on voltage-dependent Ca2+ channels in Kupffer cells. Kupffer cells were isolated from rats 2 hr after intragastric administration of ethanol (5 gm/kg intragastrically). Cytosolic free calcium concentration of cultured Kupffer cells was measured with the fluorescent Ca2+ indicator fura-2. In Kupffer cells isolated from control rats, partial replacement of extracellular Na+ by K+ caused an increase in cytosolic free calcium concentration in a concentration-dependent manner (halfmaximal effect was observed with 81 mmol/L K+), presumably because of membrane depolarization. Acute ethanol treatment in vivo shifted the concentration-response curve for K+ to the right (half-maximal effect was observed with 94 mmol/L K+) and reduced the maximal elevation of cytosolic free calcium concentration by means of K+. Significantly, the dihydropyridine-type calcium channel agonist BAY K 8644 (1 μmol/L) shifted the concentration-response curve for K+ to the left in control and ethanol-treated groups (half-maximal effect was observed with 61 and 77 mmol/L K+, respectively). Moreover, the dihydropyridine-type calcium channel blocker nitrendipine (10 μmol/L) prevented the increase in cytosolic free calcium concentration in both groups. When extracellular Ca2+ was omitted from the incubation medium, the increases in cytosolic free calcium concentration due to depolarization were prevented completely. However, direct addition of ethanol to the cell cultures was without effect. Thus these data indicate that short-term ethanol treatment in vivo reduces the probability that L-type voltage-dependent Ca2+ channels in Kupffer cells would be open. This phenomenon could be involved in the mechanism of the effect of ethanol on phagocytosis and cytokine production by Kupffer cells. (HEPATOLOGY 1993;18:400–405).

Effect of short-term ethanol treatment on voltage-dependent calcium channels in kupffer cells

Kupffer cells, the resident hepatic macrophages, are activated by calcium, and several reports indicate that their function (e.g., phagocytosis and cytokine production) is altered by ethanol. We recently found that Kupffer cells contain L-type voltage-dependent Ca2+ channels. The purpose of this study, therefore, was to evaluate the effect of short-term ethanol treatment on voltage-dependent Ca2+ channels in Kupffer cells. Kupffer cells were isolated from rats 2 hr after intragastric administration of ethanol (5 gm/kg intragastrically). Cytosolic free calcium concentration of cultured Kupffer cells was measured with the fluorescent Ca2+ indicator fura-2. In Kupffer cells isolated from control rats, partial replacement of extracellular Na+ by K+ caused an increase in cytosolic free calcium concentration in a concentration-dependent manner (half-maximal effect was observed with 81 mmol/L K+), presumably because of membrane depolarization. Acute ethanol treatment in vivo shifted the concentration-response curve for K+ to the right (half-maximal effect was observed with 94 mmol/L K+) and reduced the maximal elevation of cytosolic free calcium concentration by means of K+. Significantly, the dihydropyridine-type calcium channel agonist BAY K 8644 (1 mumol/L) shifted the concentration-response curve for K+ to the left in control and ethanol-treated groups (half-maximal effect was observed with 61 and 77 mmol/L K+, respectively). Moreover, the dihydropyridine-type calcium channel blocker nitrendipine (10 mumol/L) prevented the increase in cytosolic free calcium concentration in both groups. When extracellular Ca2+ was omitted from the incubation medium, the increases in cytosolic free calcium concentration due to depolarization were prevented completely. However, direct addition of ethanol to the cell cultures was without effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy of manidipine in the treatment of hypertension with renal impairment: A multicenter trial

The effects of 5 to 20 mg/day of manidipine, a dihydropyridine-type calcium channel blocker, on blood pressure and renal function were studied in 71 hypertensive patients with renal impairment (serum creatinine levels between 1.4 and 5 mg/dl). Thirty-two patients were followed for more than 48 weeks, and 22 patients remain on the treatment after 24 to 48 weeks. The study was interrupted in 17 patients. In 32 patients who were followed for more than 48 weeks, blood pressure was well controlled in 21 (65.6%) patients. In seven of these patients αβ- or β-blockers were added to manidipine to control blood pressure. Only 1 of 32 patients whose serum creatinine level was below 3.1 mg/dl showed deterioration of renal function during the 48 weeks. Two of the 17 patients in whom the study was interrupted died of cerebral bleeding or pneumonia. Two patients discontinued the study because of complications of myocardial infarction and retinal infarction, six withdrew because of deterioration in renal function, and the other seven patients withdrew because of poor compliance. From these studies, it was concluded that manidipine is well tolerated and effective in hypertensive patients with renal impairment (serum creatinine levels ≤3 mg/dl). If blood pressure is not well controlled in these patients, combined treatment with manidipine and αβ- or β-blockers is recommended.

The effect of nilvadipine, a dihydropyridine type calcium channel blocker, on local cerebral blood flow in rats.

The effect of nilvadipine, a dihydropyridine type calcium channel blocker, on local cerebral blood flow (lCBF) was investigated using the autoradiographic iodo[14C]antipyrine technique in rats. In control rats, lCBF in cortical areas and in the superior colliculus and inferior colliculus was higher than that in the hippocampus, septal nucleus, globus pallidus and substantia nigra. Nilvadipine (32 micrograms/kg, i.v.) increased lCBF in all structures (significantly in 11 of 21 structures) in spite of a 33% reduction in mean arterial blood pressure. These results confirm that nilvadipine has the ability to increase cerebral blood flow.

The Effect of Nilvadipine, a Dihydropyridine Type Calcium Channel Blocker, on Local Cerebral Blood Flow in Rats

The effect of nilvadipine, a dihydropyridine type calcium channel blocker, on local cerebral blood flow (1CBF) was investigated using the autoradiographic iodo[14C]antipyrine technique in rats. In control rats, 1CBF in cortical areas and in the superior colliculus and inferior colliculus was higher than that in the hippocampus, septal nucleus, globus pallidus and substantia nigra. Nilvadipine (32 μg/kg, i.v.) increased 1CBF in all structures (significantly in 11 of 21 structures) in spite of a 33% reduction in mean arterial blood pressure. These results confirm that nilvadipine has the ability to increase cerebral blood flow.

Nilvadipine, a New Calcium Channel Blocker, Reduces Ischemic Brain Injury in Rats

The effects of nilvadipine, a dihydropyridine type calcium channel blocker, on cerebral infarction induced by focal brain ischemia was studied in rats. The area of infarction was measured 24 hr after occlusion of the middle cerebral artery (MCA) in spontaneously hypertensive rats using triphenyltetrazolium chloride. Nilvadipine, given immediately after MCA occlusion, reduced the area of infarction significantly at doses of 0.32 mg/kg (i.p.) and 3.2, 10 and 32 mg/kg (p.o.). Nicardipine suppressed the area of infarction at a dose of 32 mg/kg (p.o.). The results suggest that nilvadipine is effective against ischemic brain injury.

Nilvadipine, a New Calcium Channel Blocker, Reduces Ischemic Brain Injury in Rats.

The effects of nilvadipine, a dihydropyridine type calcium channel blocker, on cerebral infarction induced by focal brain ischemia was studied in rats. The area of infarction was measured 24 hr after occlusion of the middle cerebral artery (MCA) in spontaneously hypertensive rats using triphenyltetrazolium chloride. Nilvadipine, given immediately after MCA occlusion, reduced the area of infarction significantly at doses of 0.32 mg/kg (i.p.) and 3.2, 10 and 32 mg/kg (p.o.). Nicardipine suppressed the area of infarction at a dose of 32 mg/kg (p.o.). The results suggest that nilvadipine is effective against ischemic brain injury.