PT  - JOURNAL ARTICLE
AU  - FERDINAND URTHALER
AU  - W. THOMAS WOODS
AU  - THOMAS N. JAMES
AU  - ALFRED A. WALKER
TI  - Effects of Adenosine on Mechanical Performance and Electrical Activity in the Canine Heart
DP  - 1981 Feb 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 254--260
VI  - 216
IP  - 2
4099  - http://jpet.aspetjournals.org/content/216/2/254.short
4100  - http://jpet.aspetjournals.org/content/216/2/254.full
SO  - J Pharmacol Exp Ther1981 Feb 01; 216
AB  - The effects of adenosine on electrophysiological and mechanical properties of myocardium were studied in 26 canine right ventricular trabeculae. Increasing concentrations of adenosine (1, 10 and 100 µg/ml) exert a progressively greater negative (and only negative) inotropic effect. Neither the duration of the isometric or isotonic contraction nor the duration of the relaxation was affected by adenosine. However, in muscles undergoing inotropic stimulation with norepinephrine, adenosine significantly slowed the speed of contraction by prolonging the time-dependent parameters but had no significant effect on peak force and maximum extent of shortening. In ventricular trabeculae not exposed to norepinephrine, adenosine had no significant effect on resting potential but it significantly decreased the action potential upstroke velocity. Adenosine had little or no effect on the overshoot but it significantly abbreviated the plateau phase. Both of these effects observed in action potentials could serve to enhance local electrical stability. The site of action of adenosine appears to be primarily at the cellular membrane where it may interfere with both the fast and the slow inward current. An intracellular site of action is also possible since adenosine, which readily passes cellular membrane, interferes with the speed but not with the strength of contraction when trabeculae undergo inotropic stimulation with norepinephrine. A combination of suppression of contractility and preservation of electrical stability could therefore serve as important cardioprotective action by adenosine in ischemic myocardial cells. The American Society for Pharmacology and Experimental Therapeutics, 1980