Assay of pig growth hormone preparations for metabolic activities in the rat and in man.

The possible somatotropic effect in man of porcine growth hormone (pGH) and its plasmin digest has not been comprehensively studied before. For this purpose, pGH was digested with rat or human plasmin; acrylamide gel electrophoresis showed less than 10% native pGH remaining in the digests. Native pGH and the 2 types of plasmin digest possessed similar GH potency, as measured by the weight gain assay in the hypophysectomized rat: 1-2 IU/mg. In 7 GH-deficient children and 3 adults with myotonic dystrophy, we measured the capacity of human GH (hGH), pGH, and pGH plasmin digests to cause: a) the retention of N, P, K, Na, and Cl; b) a rise in plasma free fatty acids; c) a fall in plasma alpha-amino NL d) impaired glucose tolerance; and e) hyperinsulinemia. Human GH was active in all respects at minimal effective dosages of .0168 to 0.168 IU/kg BW(3/4) per day. The pGH preparations had no detectable effect at 0.532 I.U./kg BW(3/4)/day. The data show that in man pGH and its plasmin digests possess less than 1/30, less than 1/10, and less than 1/3 the anabolic, adipokinetic, and diabetogenic potencies of hGH, respectively.