ADRENAL CATECHOLAMINES DURING AND FOLLOWING HYPOXIA IN NEONATAL RATS

Abstract

The synthesis and content of adrenal catecholamines during hypoxia (6% O2) and the following revovery period were investigated in 4-day old rats. Adrenal catecholamine synthesis, as indicated by the dopamine content of the glands, increased significantly during hypoxia. During hypoxia a significant decrease in the adrenal noradrenaline [norepinephrine NA] but not adrenaline [epinephrine] content was noted. In the recovery period following 30 min of hypoxia the NA level was rapidly restored to the control value. Hypoxia causes increased catecholamine synthesis in the immature rat adrenal gland, presumably mediated by an increased tyrosine hydroxylase activity induced via the splanchnic nerves. In the neonate rat hypoxia seems to stimulate the release of a larger proportion of NA than adrenaline from the adrenal glands when compared to the adult animal.