EFFECT OF EPIDERMAL GROWTH FACTOR ON LUNG LIQUID PRODUCTION AND CATECHOLAMINE BLOOD LEVELS IN FETAL LAMBS

Abstract

Epidermal growth factor (EGF) has been shown to accelerate fetal lung maturation, and it also has an inhibitory effect on gastric HCl secretion. Fetal lung liquid (LL) production is associated with an active Cl-transport. The effect of EGF on lung liquid production(LLP) was examined in fetal lambs with the impermeable tracer (¹²⁵I-albumin) technique. EGF given i.v. over a 4 hour period (½ injection, ½ infusion) in a total dose of 70 microg/kg to 6 fetal lambs at 0.6 to 0.95 of term resulted in a decreased LLP (6.1 ± 1.4 ml/hr vs 1.5 ± 1.1 ml/hr)^*. During EGF, K⁺ concentrations decreased in LL and plasma and remained low in LL 2-4 hours after infusion when plasma levels had normalized. Na⁺ and Cl⁻ concentrations in LL did not change significantly. Heart rate increased from 156 ± 3 to 212 ± 11^* b.p.m. Mean plasma concentrations of epinephrine increased from 27 ± 5 to 67 ± 13 pg/ml and norepinephrine increased from 257 ± 31 to 544 ± 69 pg/ml^* (5 determinations in 3 lambs). EGF infusions (20 microg/kg) during beta-adrenergic blockade with propranol (1 mg/kg + 0.2 mg/kg/hr) reduced LLP in 5 lambs from 7.5 ± 1.8 to 3.3 ± 1.2 ml/hr^* without associated tachycardia. Onset of EGF effect on LLP was within 1 hour. Liquid absorption was seen on 3 occasions. It is concluded that EGF given to fetal lambs will stimulate catecholamine secretion, and that EGF exerts an inhibitory effect on fetal lung liquid production which appears to be independent of a possible indirect catecholamine effect. ^*p <0.05. Values are Mean ± SEM

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