A comparison of the effects of verapamil and cinnarizine upon responses elicited by selective alpha 1- and alpha 2-adrenoceptor agonists in the autoperfused canine hindlimb.
In an attempt to extend the hypothesis that activation of vascular postsynaptic alpha 2-adrenoceptors requires an influx of Ca2+ ions, the effects of 2 calcium entry blocking drugs verapamil and cinnarizine have been examined as inhibitors of the pressor responses to methoxamine and B-HT 920 in autoperfused dog hindlimb preparations. Verapamil (0.1-1 mg i.a.) selectively antagonized responses to B-HT 920 and had little or no effect upon responses to methoxamine, thus supporting this hypothesis. However cinnarizine, over the dose range studied (0.1-1 mg/kg i.a.) produced quantitatively similar inhibitions of the hindlimb responses to B-HT 920 and methoxamine. These results suggest that cinnarizine may have a different site of action to verapamil in resistance vessels of the dog hindlimb.
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000818:Animals; D001381:Azepines / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002714:Chlorisondamine / Q000494:pharmacology; D002936:Cinnarizine / Q000494:pharmacology*; D004285:Dogs; D005260:Female; D006614:Hindlimb / Q000187:drug effects; D008297:Male; D008729:Methoxamine / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D010879:Piperazines / Q000494:pharmacology*; D011433:Propranolol / Q000494:pharmacology; D012039:Regional Blood Flow / Q000187:drug effects; D014700:Verapamil / Q000494:pharmacology*
D000316:Adrenergic alpha-Agonists; D001381:Azepines; D002121:Calcium Channel Blockers; D010879:Piperazines; D002936:Cinnarizine; C024763:talipexole; D011433:Propranolol; D014700:Verapamil; D008729:Methoxamine; D002714:Chlorisondamine