AJP - Heart and Circulatory Physiology, Vol 251, Issue 4 748-H755, Copyright © 1986 by American Physiological Society

ARTICLES

Age-related responses to stimulation of cardiopulmonary receptors in swine

P. M. Gootman, B. J. Buckley, S. M. DiRusso, N. Gootman, A. C. Yao, P. E. Pierce, P. G. Griswold, M. D. Epstein, H. L. Cohen and D. B. Nudel

Cardiovascular responses to stimulation of cardiopulmonary receptors were evaluated in standard breed developing swine (1-2 days, 1-2 wk, and 2 mo of age) and sexually mature miniswine anesthetized with 0.25-0.50% halothane in O2. Cryptenamine, a mixture of veratrum viride alkaloids (VVA), was administered as right atrial or left ventricular bolus injections in doses of 5-20 micrograms/kg. In developing swine, mean aortic pressure (AoP) decreased after 10-20 micrograms/kg VVA in 1- to 2-wk olds and after 5-20 micrograms/kg VVA in 2-mo olds. Bradycardia was always elicited. Renal (Ren) and femoral (Fem) vasodilation occurred in the 1- to 2-wk-old and 2-mo-old groups after 5-20 micrograms/kg VVA. Mesenteric (Mes) vasodilation was elicited with 10-20 micrograms/kg VVA in the 1- to 2-wk-old group and with 5-20 micrograms/kg VVA in 2-mo olds. In the 1- to 2-day-old group, VVA did not significantly alter Ren, Fem, and Mes vascular resistance. In mature miniswine, 20 micrograms/kg VVA elicited decreases in AoP and heart rate that were similar in magnitude to responses obtained with only 5 micrograms/kg VVA in dogs. Cardiovascular responses to VVA were abolished after bilateral vagotomy but were not altered after denervation of the carotid sinuses. The results indicate postnatal maturation of the Bezold-Jarisch reflex in swine.

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