Potassium currents in atrial and ventricular myocytes from a rat model of cirrhosis.
The underlying mechanisms for the electrophysiological abnormalities that develop as a consequence of cirrhosis of the liver have been studied by recording three different K+ currents in mammalian heart tissue. Single myocytes from the atria and ventricles of sham-operated and bile ductligated (BDL) cirrhotic adult rats were current and voltage clamped using standard whole cell methods. In ventricular myocytes from cirrhotic animals, measurements of the current-voltage relationships, voltage dependence of inactivation, and reactivation kinetics of K+ currents showed that the only significant functional changes (within the physiological range of membrane potentials) were decreases in the density of expression of 1) I(t), a Ca(2+)-independent transient outward K+ current, and 2) Isus, a delayed rectifier K+ current. The decreases in I(t) and Isus contribute to the prolonged Q-T interval of the electrocardiogram that has been described in cirrhotic patients. Measurement of K+ currents in atrial myocytes demonstrated that there were no significant differences in any of the K+ current densities between sham and BDL animals, although reactivation kinetics of I(t) were slowed somewhat.
Ward
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Department of Physiology and Biophysics, Faculty of Medicine, University of Calgary, Alberta, Canada.
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Lee
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Giles
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D000818:Animals; D016275:Atrial Function; D001652:Bile Ducts; D002469:Cell Separation; D004553:Electric Conductivity; D008026:Ligation; D008106:Liver Cirrhosis, Experimental / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D009206:Myocardium / Q000473:pathology; D011188:Potassium / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D016276:Ventricular Function
D011188:Potassium