Role of growth hormone in the amino acid-induced acute rise in renal function in man

Abstract

To examine whether plasma growth hormone is necessary for the amino acid-induced rise in effective renal plasma flow (ERPF, PAH clearance) and GFR (inulin clearance), arginine HCl, 500 mg/kg, was infused for 30 minutes into eight normal and six growth hormone-deficient individuals. During infusion, ERPF increased in the normal and growth hormone-deficient subjects by 28.9 +/- 11.4 SD-% (P less than 0.01) and 46.5 +/- 14.4% (P less than 0.001). GFR rose by 23.7 +/- 5.9% (P less than 0.05) and 42.7 +/- 29.1% (P less than 0.001) in the two groups. Plasma growth hormone rose only in the normal subjects, while glucagon increased in both groups. Infusion of arginine HCl, 200 mg/kg, into normals increased ERPF and GFR without increasing plasma osmolality. Lower arginine doses essentially did not affect ERPF, GFR, growth hormone, or glucagon. Infusion of D-glucose into normals raised plasma osmolality as high as with arginine HCl, 500 mg/kg, but increased ERPF only slightly and not GFR; D-glucose infusion caused a delayed rise in growth hormone that was unassociated with an increase in ERPF or GFR. An infusion of ammonium chloride with sodium chloride, which provided an amount of chloride similar to the 500 mg/kg arginine HCl dose, did not change ERPF and GFR; this suggests that the chloride load did not cause the altered renal hemodynamics stimulated by arginine HCl. These findings indicate that neither normal plasma growth hormone levels nor a rise in growth hormone mediates the arginine-induced acute increase in ERPF or GFR. This effect is also not due to the osmolar load but could be caused by the rise in plasma glucagon.