Verapamil as an apparent competitive antagonist of the serotonin receptor of rabbit isolated aorta.
The actions of four Ca2+-antagonists (verapamil, diltiazem, nifedipine and flunarizine) were tested on serotonin- (5-HT-) induced contraction of rabbit isolated aorta. Verapamil produced a dose-dependent, parallel shift to the right of the concentration-response curve for 5-HT (pA2 approximately equal to 7.13; Schild slope approximately equal to 1.01), indicative of competitive antagonism. The effects of diltiazem, nifedipine and flunarizine were much less pronounced and best characterized as non-competitive interactions. The effect of verapamil, which likely involves its antagonism of smooth muscle 5-HT2-receptors, might be useful in explaining its therapeutic actions and/or its side-effects.
Auguet
M
M
Delaflotte
S
S
Clostre
F
F
DeFeudis
F V
FV
D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000378:metabolism; D001667:Binding, Competitive / Q000187:drug effects; D002936:Cinnarizine / Q000031:analogs & derivatives / Q000494:pharmacology; D004110:Diltiazem / Q000494:pharmacology; D005444:Flunarizine; D005711:Gallopamil / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D009543:Nifedipine / Q000494:pharmacology; D011817:Rabbits; D011985:Receptors, Serotonin / Q000187:drug effects*; D014700:Verapamil / Q000494:pharmacology*
D011985:Receptors, Serotonin; D005711:Gallopamil; D002936:Cinnarizine; D014700:Verapamil; D004110:Diltiazem; D009543:Nifedipine; D005444:Flunarizine