GROWTH-HORMONE (GH) RECEPTOR AND GH-BINDING PROTEIN-DEFICIENCY IN THEGROWTH FAILURE OF POTASSIUM-DEPLETED RATS

Potassium (K+) deficiency is associated with growth retardation in bot h man and experimental animals. Growth hormone (GH) administration to such animals prevents, to some extent, weight loss and selective muscl e atrophy, but does not affect tail and tibia length even with supraph ysiological doses. The present study was undertaken to investigate the possible effect of K+ deficiency on the hepatic GH receptor and GH-bi nding protein (BP). Young female Wistar rats were maintained on K+-def icient fodder and distilled water, and compared with pair-fed and ad-l ibitum-fed control groups. After 15 days GH-BP and electrolytes were m easured in sera, GH receptors were studied in Liver membranes by I-125 -labeled human GH binding and muscles were weighed and saved for elect rolyte measurements. K+-deficient rats showed complete growth arrest c ompared with an intermediate weight gain of the pair-fed group. Serum K+ was very low, at 1.5 + 0.1 mmol/l, compared with the mean value of 5.3 mmol/l of control animals. Somatogenic and lactogenic receptors in Liver membranes and serum GH-BP levels were significantly (P < 0.05) lower in K+ deficiency, as compared with their pair-fed controls. Live r GH receptors correlated significantly (P < 0.05) with serum GH-BP le vels. The growth variables correlated positively with both hepatic som atogenic and lactogenic receptors and serum GH-BP levels, with correla tion coefficients that were highest against serum GH-BP and lowest aga inst liver lactogenic receptors. Serum and muscle K+ correlated signif icantly (P < 0.05) with both liver GH receptors and serum GH-BP, with correlation coefficients that were higher against serum GH-BP. Lactoge nic receptors had a lower or no correlation. It is concluded that GH r eceptor deficiency may be involved in the growth retardation of K+ def iciency.