RT Journal Article
SR Electronic
T1 MYOCARDIAL NA/K ADENOSINE TRIPHOSPHATASE ACTIVITY DURING REVERSAL OF OUABAIN TOXICITY WITH DIPHENYLHYDANTOIN
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 594
OP 598
VO 179
IS 3
A1 ROBERT C. SPAIN
A1 CHARLES A. CHIDSEY
YR 1971
UL http://jpet.aspetjournals.org/content/179/3/594.abstract
AB The effect of diphenyihydantoin (DPH) on myocardial Na/K adenosine triphosphatase (ATPase) activity was examined to investigate a potential mechanism of its action in reversing digitalis-induced arrhythmias. DPH was shown to stimulate control ATPase, but only with a high (50/0.2 mM) Na/K ratio through which threshold activation of the enzyme was achieved. In vitro, DPH did not stimulate the partially inhibited enzyme prepared from dogs in which arrhythmias had been produced by infusion of toxic amounts of ouabain. Neither was any reactivation of the ouabain-inhibited enzyme seen when DPH was administered in vivo to reverse toxic arrhythmias produced by ouabain infusion. Furthermore, DPH was ineffective in preventing partial or complete enzyme inhibition produced by ouabain in vitro. Thus, it is suggested that DPH may reverse digitalis-induced arrhythmias through an action other than stimulation of digitalis-inhibited myocardial Na/K ATPase. © 1971 by The Willams & Wilkins Co.