Circulatory effects of chemical sympathectomy in fetal, neonatal, and adult sheep
- 1 July 1982
- journal article
- research article
- Published by American Physiological Society in American Journal of Physiology-Heart and Circulatory Physiology
- Vol. 243 (1), H113-H122
- https://doi.org/10.1152/ajpheart.1982.243.1.h113
Abstract
Circulatory effects of chemical sympathectomy with 6-hydroxydopamine (6-HD), including changes in vascular sensitivity to neurotransmitters, were investigated in chronically instrumented unanesthetized fetal, neonatal, and adult sheep. In all animals acute response to 6-HD consisted of hypertension and tachycardia, which lasted 2-3 h. Chronic phase of sympathetic ablation then followed during which arterial pressure and heart rate of sympathectomized fetus and neonate returned to and remained at levels observed in intact animals, whereas adult sheep were slightly hypotensive throughout this period. In all animals supersensitivity of peripheral circulation to norepinephrine occurred, but only the fetus exhibited supersensitivity to acetylcholine and isoproterenol. Our conclusions are as follows: 1) acute phase of chemical sympathectomy in fetal, neonatal, and adult sheep simulates strong adrenergic stimulation; 2) absence of significant alteration in arterial pressure of fetus and neonate during the chronic phase of sympathectomy suggests a minor role for the adrenergic system in the maintenance of resting tone of peripheral circulation; and 3) on the basis of present and previous data, we postulate that the supersensitivity of fetal circulation to acetylcholine and isoproterenol may be secondary to changes occurring in pulmonary vascular bed.This publication has 4 references indexed in Scilit:
- Cardiovascular Reactivity of Neonatal and Adult Sheep to Autonomic Stimuli during Adrenergic DepletionNeonatology, 1978
- Increased circulating plasma catecholamines and plasma renin activity in dogs after chemical sympathectomy with 6-hydroxydopamineCanadian Journal of Physiology and Pharmacology, 1977
- Blood and plasma volume changes in dogs after sympathectomy with 6-hydroxydopamineCanadian Journal of Physiology and Pharmacology, 1977
- Autonomic control of cardiovascular functions during neonatal development and in adult sheep.Circulation Research, 1977