Action potentials in the sensory vagus at the time of coronary infarction

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Abstract
In the anesthetized nonthoracotomized dog, impulse traffic of demonstrated left ventricular origin in the cervical sensory vagus was monitored before, during, and up to 1 hr after coronary infarction with the necrotizing agent hexachlorotetrafluorobutane (Hexa). Various combinations of left ventricular pressure pulse (LVP), aortic pressure (AP), lead II ecg, respiration (R), and 1st derivation (dP/dt) of LVP were recorded simultaneously. Two bursts of action potentials in a single cardiac cycle observed in the control period, one during isometric contraction and the other beginning during ejection and lasting a varying period of time, were converted into one shorter burst at higher frequency at the time of Hexa infarction. dP/dt increased at the same time. Hypotension, bradycardia, and decreased systolic LVP were the hemodynamic events at the time of infarction. Thoraco-tomy later and exploration of the heart with touch pressure demonstrated that the receptors studied were located in the infarcted area in 15 of 16 cases. Relation of these results to information theory and to a possible physiological role for Bezold reflexes are discussed. Studies on acetylcholine, epinephrine, and Veriloid are included.

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