Abstract
Summary
In spinal cats vagotomized and administered sufficient propranolol to block cardiac beta-receptors, the effect of vagal stimulation of the myocardium was studied. With this stimulation, a bradycardia was sustained for 1- to 4-hr intervals. Examination of the myocardial tissue from atria and ventricles revealed, however, no myofibrillary or vascular changes. Since these results indicate that this vagal stimulation did not produce myocardial necrosis, alterations in cardiac tissue attributed by other investigators to parasympathetic activation would appear to involve secondary sympathetic effects.
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