Impairment of Ca release from mammalian ventricular sarcoplasmic reticulum by the calcium channel agonist Bay K 8644.
Positive inotropic concentration of the Ca-channel agonist, Bay K 8644, depressed contraction of canine right ventricular trabecula immediately after a rest period of 8 min, without decreasing action potential plateau amplitude. In contrast, high external Ca and ouabagenin caused only a slight decrease in post-rest contraction. Bay K 8644-induced post-rest depression was inversely related to the extracellular Ca concentration. Hence it could not be due to cellular Ca overload. Since post-rest potentiation is due to increased contribution of Ca from the sarcoplasmic reticulum, these results suggest that Bay K 8644 decrease the amount of releasable Ca from this structure during rest.
Hryshko
L V
LV
Department of Pharmacology & Therapeutics, University of Manitoba, Faculty of Medicine, Winnipeg, Canada.
Bose
D
D
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002120:Calcium Channel Agonists / Q000494:pharmacology*; D004285:Dogs; D005260:Female; D006352:Heart Ventricles / Q000378:metabolism; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*
D002120:Calcium Channel Agonists; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D002118:Calcium