@article {Prinzmetal659, author = {Myron Prinzmetal and Kazuo Ishikawa and Hiroshi Oishi and Emir Ozkan and Jiro Wakayama and James M. Baines}, title = {EFFECTS OF QUINIDINE ON ELECTRICAL BEHAVIOR IN CARDIAC MUSCLE}, volume = {157}, number = {3}, pages = {659--664}, year = {1967}, publisher = {American Society for Pharmacology and Experimental Therapeutics}, abstract = {The effects of quinidine on the canine heart were investigated in situ. In the anesthetized dog, the i.v. injection of quinidine sulfate causes prolongations of the RR, PQ, QRS and QT interval in surface electrograms. Intracellular potentials were recorded from the left ventricle. Quinidine causes a slight but significant prolongation of the duration of the membrane action potential. It causes a great decrease in the upstroke velocity of the membrane action potential. There are insignificant changes in the magnitudes of the membrane action potential, membrane resting potential and overshoot. The prolongation of the QRS duration in surface electrograms is associated with the decrease in the upstroke velocity of the membrane action potential. The prolongation of the QT interval corresponds to the prolongation of the duration of the membrane action potential. The prolongation in the duration of the membrane action potential and the decrease in the upstroke velocity prolong the effective refractory period. The prolongation of the effective refractory period and the decrease of the automaticity may be considered to be antiarrhythmic actions of quinidine. {\textcopyright} 1967 by The Williams \& Wilkins Company}, issn = {0022-3565}, URL = {https://jpet.aspetjournals.org/content/157/3/659}, eprint = {https://jpet.aspetjournals.org/content/157/3/659.full.pdf}, journal = {Journal of Pharmacology and Experimental Therapeutics} }