CATECHOLAMINES INHIBIT GROWTH IN FETAL SHEEP IN THE ABSENCE OF HYPOXEMIA

To evaluate contributions of catecholamines to inhibition of growth du ring chronic hypoxemia or severe undernutrition, epinephrine (Epi; 0.2 5-0.35 mu g.kg(-1).min(-1)) or norepinephrine (NE; 0.5-0.7 mu g.kg(-1) .min(-1)) was administered to normoxemic fetuses in twin-pregnant ewes for 8-12 days, from 125 to 127 days of gestation. Both had similar ef fects and decreased fetal weight by similar to 20% relative to control twins (P < 0.01). Weight gain ceased during infusion of Epi or NE (-2 1 +/- 14.8 or 14 +/- 20.9 g/day), whereas controls gained 93 +/- 13.2 g/day (P < 0.01). Effects on tissues and organs varied, spleen and thy mus being most retarded, whereas brain weight and skeletal measures we re affected little. Selected muscles from infused fetuses weighed 72% of those in controls. Growth ceased during infusion (P < 0.001). Weigh t gain of hindlimb bones was negligible, but length increased at 56% o f control rates. Arterial blood CO2 and plasma insulin were decreased (P < 0.001), but plasma glucose, growth hormone, and blood oxygenation increased (P < 0.001). Actions of Epi and NE could underlie asymmetri cal growth retardation occurring in many adverse physiological situati ons during fetal development.