title: Ca2+, histamine antagonists and relaxation to electrical impulses in dog coronary artery.
abstract: Isolated dog coronary arteries relax in response to electrical stimulation (0.1-8.0 Hz, 9 V, 1.0 ms) following contraction induced by serotonin. Cimetidine, metiamide and ranitidine inhibited this relaxation. The relaxation was not blocked by pyrilamine. Reducing the concentration of Ca+ (0.1 mM) decreased the rate of relaxation whereas relaxation was more rapid when the Ca2+ concentration was increased (3.2 mM). These results suggest that relaxation to electrical stimulation is modulated by Ca2+ and by the H2-subclass of histamine receptors.
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology* / Q000502:physiology; D003331:Coronary Vessels / Q000187:drug effects; D004285:Dogs; D004558:Electric Stimulation; D005260:Female; D006633:Histamine Antagonists / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009126:Muscle Relaxation / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D012701:Serotonin / Q000494:pharmacology
chemical_list: D006633:Histamine Antagonists; D012701:Serotonin; D002118:Calcium