Cholera toxin enhances ischemia-induced arrhythmias in the isolated rat heart--involvement of a guanine nucleotide binding protein (Gs).
Cholera toxin (CTX) at a dose, which disturbed the intestinal functions, was administered into the rat via the tail vein. At 3 hr after injection, the heart was removed and perfused or subject to global ischemia in the Langendorff isolated heart preparation. Electrocardiogram (ECG) was recorded throughout the experiment. The myocardial cAMP content was measured in the intact non-ischemic heart, and in the isolated ischemic heart at 2.5, 5 and 10 min after ischemia. It was found that the incidence and severity of malignant ventricular arrhythmias including ventricular tachycardia (VT) and ventricular fibrillation (VF) was significantly increased during ischemia in the CTX treated group. The cAMP content was also significantly increased in the CTX treated group in both intact non-ischemic and ischemic hearts, indicating an activation of the guanine nucleotide regulatory protein (Gs). The results of the present study provide evidence that activation of Gs during ischemia may also contribute to the genesis of arrhythmia.
Huang
X D
XD
Department of Physiology, University of Hong Kong.
Wong
T M
TM
D000818:Animals; D001145:Arrhythmias, Cardiac / Q000209:etiology* / Q000503:physiopathology; D002772:Cholera Toxin / Q000494:pharmacology*; D003327:Coronary Disease / Q000150:complications / Q000378:metabolism* / Q000503:physiopathology; D000242:Cyclic AMP / Q000032:analysis; D004562:Electrocardiography; D005260:Female; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006339:Heart Rate; D009206:Myocardium / Q000032:analysis / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D002772:Cholera Toxin; D000242:Cyclic AMP; D019204:GTP-Binding Proteins