NEONATAL ADRENOCORTICAL FUNCTION AND ITS POSSIBLE RELATION TO THE UPTAKE OF MACROMOLECULES BY THE SMALL INTESTINE OF THE GUINEA-PIG AND RABBIT

Abstract

SUMMARY: Plasma cortisol and corticosterone were separated by Sephadex LH-20 chromatography. The high concentration of plasma cortisol immediately after birth in the guinea-pig coincided with the decline in ¹²⁵I-labelled polyvinyl pyrrolidone (PVP) uptake (closure) between 48 and 72 h. Similarly, in the rabbit, plasma cortisol concentration was increasing at the time of closure, 18–21 days after birth. These results suggest that there is a correlation between the time when the concentration of the main plasma adrenocortical steroid rises and the time when the neonatal small intestine ceases to take up PVP.