Dopamine antagonist effect of verapamil on isolated perfused rabbit ear artery.
Rabbit ear arteries were isolated and perfused with Krebs-bicarbonate solution. Brief periods of supramaximal nerve stimulation caused reproducible constriction of the arteries, which was inhibited by dopamine at concentrations ranging from 3.3 X 10(-9) to 3.3 X 10(-7) M. The inhibitory effect of dopamine was antagonized by sulpiride and by verapamil. The dose-response curve to dopamine was shifted to the right by both sulpiride and verapamil, indicative of competitive inhibition. The dopamine antagonist activity of verapamil does not appear to be a consequence of its Ca++ channel inhibitory activity because other calcium antagonists (e.g., nitrendipine and diltiazem) had no similar action.
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D001158:Arteries / Q000187:drug effects; D002121:Calcium Channel Blockers / Q000494:pharmacology; D003864:Depression, Chemical; D004110:Diltiazem / Q000494:pharmacology; D018492:Dopamine Antagonists; D004305:Dose-Response Relationship, Drug; D005260:Female; D009543:Nifedipine / Q000031:analogs & derivatives / Q000494:pharmacology; D009568:Nitrendipine; D010477:Perfusion; D011817:Rabbits; D013469:Sulpiride / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects*; D014700:Verapamil / Q000494:pharmacology*
D000317:Adrenergic alpha-Antagonists; D002121:Calcium Channel Blockers; D018492:Dopamine Antagonists; D013469:Sulpiride; D009568:Nitrendipine; D014700:Verapamil; D004110:Diltiazem; D009543:Nifedipine