Calcium antagonistic properties of nicardipine, a dihydropyridine derivative assessed in isolated cerebral arteries and cardiac muscle.
Calcium antagonistic properties of nicardipine (YC-93), a 1,4-dihydropyridine derivative, were studied in isolated cerebral artery and cardiac tissues of rabbits and dogs. Calcium antagonism was assessed in electrically stimulated rabbit basilar artery. Nicardipine at 10(-7) mol/l shifted to the right the dose-response curve for Ca of the phasic contraction evoked by electrical stimulation with an alternating current, and at higher concentration it reduced the maximum tension and slope of the dose-response curve. Nicardipine inhibited the augmented contraction produced by high K, k-strophanthin and 5-hydroxytryptamine. It also caused dose-dependent inhibition of 45Ca uptake enhanced by 80 mmol/l K in dog basilar artery, and had a slight effect on the resting 45Ca uptake. In rabbit basilar artery treated with saponin, nicardipine in a dose of 10(-5) mol/l had no apparent effect on the increase in tension induced by excess Ca. Nicardipine had negative inotropic and chronotropic actions. These results suggest that nicardipine, like nifedipine, has a relative high vascular selectivity, and primarily acts by inhibiting Ca influx through the plasma membrane of vascular and cardiac tissues.
D000818:Animals; D001488:Basilar Artery / Q000187:drug effects; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002301:Cardiac Glycosides / Q000494:pharmacology; D002536:Cerebral Arteries / Q000187:drug effects; D003529:Cymarine / Q000494:pharmacology; D004285:Dogs; D004558:Electric Stimulation; D005260:Female; D006321:Heart / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D009200:Myocardial Contraction / Q000187:drug effects*; D009529:Nicardipine; D009543:Nifedipine / Q000031:analogs & derivatives* / Q000494:pharmacology; D011817:Rabbits; D012701:Serotonin / Q000494:pharmacology; D013045:Species Specificity
D002121:Calcium Channel Blockers; D002301:Cardiac Glycosides; D012701:Serotonin; D009529:Nicardipine; D009543:Nifedipine; D003529:Cymarine