Cardiac response to cephalic ischemia

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Abstract
In the Innervated, isovolumetrlc, canine left ventricle preparation, cephalic ischemia of 1-min. duration results in bradycardla and an enhancement of ventricular contractility. Respiratory activity Is at first stimulated, then depressed. The changes in cardiac behavior are induced by a simultaneous discharge of both sympathetic and parasympathetlc medullary centers. Parasympathetlc influences are prepotent at the sinoatrial node, whereas sympathetic influences predominate at the ventricular myocardium. Vagal influences do exert a significant inhibitory effect upon the ventricular myocardium during cephalic ischemia; however, at the end of 1 min. of cephalic ischemia, the increase in peak ventricular pressure is only 1/2 as great before bilateral vagotomy as after vagotomy.