Why the study?
Does vagal stimulation produce myocardial necrosis in spinal cats vagotomized and administered propranolol?
Does vagal stimulation produce myocardial necrosis in spinal cats vagotomized and administered propranolol?
Vagal stimulation does not directly produce myocardial necrosis when sympathetic effects are blocked, suggesting that previously reported parasympathetic-induced tissue alterations are likely due to secondary sympathetic effects.
Challenges direct vagal causation of necrosis in blocked models; hypothesis-generating for sympathetic mediation and not ready for clinical translation.
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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Corley et al. (1973) studied this question.
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