Relaxation of carbocyclic thromboxane A2-induced contractions of isolated coronary arteries by nifedipine.
+/- Carbocyclic thromboxane A2 (2.9 x 10(-7) mol/l) contracted isolated rings of cat coronary artery. These contractions could be partly inhibited by low concentrations of nifedipine (50% inhibitory concentration - IC50 = 6.8 x 10(-8) mol/l) and completely relaxed by papaverine. Relaxation of thromboxane-induced coronary spasm may contribute to the effectiveness of calcium antagonists in variant angina, which may be caused or exacerbated by thromboxane A2 release from platelets.
D000818:Animals; D002415:Cats; D003331:Coronary Vessels / Q000187:drug effects*; D004121:Dimethyl Sulfoxide / 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*; D010208:Papaverine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology*; D013928:Thromboxane A2 / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors*; D013931:Thromboxanes / Q000037:antagonists & inhibitors*
D011725:Pyridines; D013931:Thromboxanes; C024587:thromboxane A2, carbocyclic; D013928:Thromboxane A2; D011189:Potassium Chloride; D010208:Papaverine; D009543:Nifedipine; D004121:Dimethyl Sulfoxide