Intestinal uptake and retention of copper in the suckling rat, Rattus rattus--III. Effects of closure.

The ileum of suckling rats contains a high level of copper, most of which is concentrated within cytoplasmic vesicles of the enterocytes. Intestinal closure, 20-21 days after birth, results in the replacement of enterocytes by cells devoid of these vesicles and there is a concomitant fall in the level of copper in the ileum. Administration of cortisone acetate (0.5 mg/g body wt) to 5-day-old rats results in premature loss of copper-laden ileal enterocytes and an 80-90% decrease in the ileal copper concentration. The loss of copper is mainly from the soluble fraction of the tissue and is proportionally greater from the high molecular weight-protein fraction rather than from the copper complex.