Growth hormone action is blunted by acidosis in experimental uremia or acid load.

ABSTRACT

The effects of rhGH (H) daily injection (2 IU/d) and of vehicle (V) during two weeks were studied in young (60 g) growing rats. Experiment I was performed in uremic rats (mean plasma creatinine 65-71 mumol/l) either acidotic (mean HCO3-11.5 mmol/l UAH, n = 20; UAV, n = 18), or with corrected acidosis by addition of NaHCO3 in the diet (mean HCO3-26 mmol/l UBH, n = 25; UBV, n = 23). Experiment II used rats with normal renal function (plasma creatinine 25 mumol/l), either non-acidotic but food restricted to the dietary intake of uremic rats (CRH n = 18, CRV n = 18), or rendered acidotic by NH4Cl (CAH n = 16, CAV n = 16). GH induced an augmentation of body weight and length gains in non-acidotic uremic rats (+33% and +41% p < 0.01), and in non-acidotic food restricted rats (+13% and 42% p < 0.05 and p < 0.0001). This was associated with increased protein synthesis rate in muscle and with little change of food intake as well as of plasma IGF 1. Plasma IGF 1 kept the same relationship to food intake, regardless of treatment, but length gain for each level of plasma IGF 1 was enhanced by GH in GH responding groups. In both acidotic rat groups, GH altered none of the parameters studied. Thus 1) the presence of severe metabolic acidosis blunts the response to GH in uremic and non-uremic rats. 2) The increment of growth rate does not depend on a rise of plasma IGF 1.