Changes in rat liver monooxygenase activities after administration of atenolol, nifedipine and diltiazem alone and in combination.

The effects of the Ca2+ antagonists nifedipine (NF) and diltiazem (DL) and of the cardioselective beta 1-adrenergic blocking agent atenolol (AT) on the hexobarbital (HB) sleeping time and on the activity of some liver drug-metabolizing enzyme systems in male Wistar rats were studied. Two hours after single oral administration, atenolol (150 mg/kg) did not change hexobarbital sleeping time, while nifedipine (50 mg/kg) and diltiazem (30 mg/kg) prolonged it by 171.2 and 99.

Combined effect of propranolol with nifedipine or with diltiazem on rat liver monooxygenase activities.

The effects of two Ca2+ antagonists nifedipine (NF) and diltiazem (DL) and of the nonselective beta-adrenergic blocking agent propranolol (PR) on the hexobarbital (HB) sleeping time and on the activity of some liver drug-metabolizing enzyme systems in male Wistar rats were studied. Two h after single oral administration PR (50 mg/kg) did not change HB sleeping time, while NF (50 mg/kg) and DL (30 mg/kg) prolonged it by 171.2 and 99.

In vivo induced desensitization of beta-adrenoceptors in rat lung. Effect of nitrendipine.

The effect of nitrendipine on desensitization of beta-adrenoceptors induced by isoprenaline was investigated using rat lungs. Rats were treated with saline, isoprenaline, nitrendipine, or nitrendipine + isoprenaline. After 7 days of treatment, tracheas were isolated and the dissociation constant (Kb) for the propranolol-beta-receptor complex was determined.

Effects of beta-adrenoceptor blocker pindolol, calcium antagonist verapamil and their combination on retention in step-down- and shuttle-box-trained rats and on brain biogenic monoamines.

The effects of the beta-adrenoceptor blocker pindolol and the calcium antagonist verapamil administered alone or in combination on retention in step-down- and shuttle-box-trained rats and on the biogenic monoamine levels in the frontal cortex and hippocampus were examined. The chronic oral treatment with pindolol impaired retention in step-down- and shuttle-box-trained rats, decreasing the dopamine (DA) and noradrenaline (NA) levels and increasing the serotonin (5-HT) levels in the cortex and hippocampus. Verapamil did not influence retention in step-down- and shuttle-box avoidance situation and the biogenic monoamine levels in the frontal cortex and hippocampus.

Effects of flunarizine and nitrendipine on electroconvulsive shock- and clonidine-induced amnesia.

This study was designed to examine the calcium channel blockers flunarizine and nitrendipine for their ability to prevent electroconvulsive shock (ECS)- or clonidine-induced deterioration of the inhibitory avoidance performance (step-down) in rats. Flunarizine (10 mg/kg) and nitrendipine (40 mg/kg) were found to prevent the ECS- or clonidine-provoked amnesia after oral administration for 12 days. The mechanisms of action of the two drugs are considered.