AJP - Heart and Circulatory Physiology, Vol 246, Issue 5 664-H670, Copyright © 1984 by American Physiological Society
Ouabain-induced reflex coronary vasodilatation mediated by cardiac receptors
B. Trimarco, S. Chierchia, B. Ricciardelli, A. Cuocolo, M. Volpe, L. Sacca and M. Condorelli
Experiments were performed to determine the effects of digitalis-induced
stimulation of cardiac receptors on the coronary circulation. In
chloralose-anesthetized dogs, left circumflex coronary artery was perfused
at constant flow, and heart rate was maintained constant by electric
pacing. Ouabain injection in the perfused coronary artery produced a
significant decrease in coronary perfusion pressure. Epicardial application
of lidocaine completely blocked the reflex response. Vagotomy also
prevented this reflex response. Sympathetic blockade with intravenous
guanethidine or intracoronary phentolamine partially reduced the reflex
coronary vasodilatation. Intracoronary atropine also partially reduced the
coronary vasodilator response to ouabain. The combined administration of
guanethidine and atropine completely abolished the coronary reflex
response. These data demonstrate that ouabain can evoke reflex coronary
vasodilation by stimulating cardiac receptors. This reflex response is
mediated by activating cholinergic vasodilator fibers and inhibiting
sympathetic vasoconstrictor fibers.
