The American Journal of Clinical Nutrition 33: MARCH 1980, pp. 617-620. Printed in U.S.A. 617 Leucocyte sodium transport and dietary zinc in protein energy maInutrition3 John Patrick, Barbara E. Golden, and Michael H. N. Golden ABSTRACT Zinc supplementation of children who were just completing a period of rapid “catch-up” growth during recovery from severe malnutrition was found to stimulate sodium transport in their leucocytes. These results suggest that zinc status should be studied in the large number of serious illnesses now known or thought to be associated with impaired sodium transport. Am. J. Clin. Nutr. 33: 617-620, 1980. Abnormalities of zinc metabolism and so- dium transport occur in a number of diseases including malnutrition (1-3). Any precise re- lationship between zinc and sodium metabo- lism is difficult to define because of the lack of adequate methods for the assessment of zinc status. However, during a study of zinc supplementation in severely malnourished children it was noticed that leucocyte sodium transport was stimulated. Leucocytes ob- tamed from severely malourished children have high intracellular sodium values, low intracellular potassium values, and dimin- ished glycoside sensitive sodium transport (3). These defects are usually remedied in 3 to 4 weeks of high energy feeding but if the chil- dren are maintained on the high energy, fat supplemented diet for more than 50 days leucocyte intracellular potassium again be- gins to fall and sodium to rise. It is in this group of children that we have demonstrated an effect of zinc. Patients and methods Seven children ages 14 to 21 months and weighing 8.4 to 9.0 kg were studied. Six children were initially marasmic and one infant (CD) had marasmic kwashi- orkor according to the Wellcome criteria (4). At the time of the study the children had been receiving the rehabil- itation diet for from 52 to 97 days, had lost their edema (CD) and had regained their expected weight for height based on the Boston standards (5). The diet was either a soya formula (RD, GC, CD, DC) (Sobee, Mead John- son) or a cow’s milk formula (CC, NW, OF) (Pelargon, Nestle) supplemented with arachis oil (55 ml/liter) to provide 35 g protein, 1350 kcal, and 2.3 mg Zn per liter of feed. For the purposes of the study the children were supplemented with 1.0 mg Zn per kilogram per day in the form of zinc acetate. Blood samples were obtained before and after 5 to 7 days of zinc supplementation for the measurement of plasma Na, K, and Zn and also for the measurement of leucocyte Na, K, and sodium transport. The cells were obtained from heparinized whole blood by dextran sed- imentation, differential centrifugation, and hypotonic lysis of the remaining red cells. The cells were labeled with 22Na at 37 C in Kreb’s bicarbonate buffer (pH 7.4) without added zinc and then washed preliminary to the measurement ofthe rate constant for sodium efflux with and without ouabain (I x iO4 M). Intracellular electro- lytes were measured using ‘25I-labeled PVP (MW 45,000) as the extracellular fluid marker. The methods have been described in detail elsewhere (6-8). Plasma zinc was measured by atomic absorption spectrophotometry and plasma sodium and potassium by flame photometry. The investigation was approved by the local ethics committee. Written parental consent was obtained after the nature of the study and in particular its lack of immediate benefit to the child had been explained. The studies were performed according to the principles of the Declaration of Helsinki. Statistical analyses were performed using the paired t test except in the case of sodium efflux rate in which the Walsh test was used (9). Results All results are expressed as means and SEM. There was no change in food consump- tion, 1 18 ± 7.3 ml/kg per day nor rate of weight gain, 6.4 ± 1. 1 g/kg per day during the study. The clinical condition of the chil- dren was also unchanged. ‘From the Tropical Metabolism Research Unit, Uni- versity of the West Indies, Kingston 7, Jamaica. 2 Supported by grants from the Wellcome Trust to J.P. and MG. and from the Research Corporation of America to B.G. Address reprint requests to: Dr. John Patrick, Renal Laboratory, Medical Unit, St. Thomas’ Hospital, Lon- don S.E.1, England. by guest on April 12, 2012 www.ajcn.org Downloaded from