METABOLISM OF [2-14C] PYRUVATE IN NORMAL, ACROMEGALIC AND HGH-TREATED HUMAN SUBJECTS

Abstract

ABSTRACT In 4 studies on 3 acromegalic patients, who had normal iv glucose tolerance and high insulin response to infused glucose (Al), the oxidation to 14CO2 of [2-14C] pyruvate (injected intravenously in trace amount after overnight fast) was not different from that in 9 studies of 9 nonacromegalic »high insulin responders« (Ni). In 4 studies on 3 other acromegalic patients, who had low glucose tolerance and less insulin response to glucose (A2), the formation of 14CO2 was reduced to ½–⅔ that of Al or N1 and was about proportionate to the reduction in glucose tolerance. In A2 the 14CO2 formation was slightly lower than the mean for 10 studies with 7 non-acromegalic subjects, who were »low insulin responders« with normal or low glucose tolerance (N2). Among non-acromegalics expiration of 14CO2 was significantly lower in N2 than in N1. Among 4 non-acromegalic subjects treated with human growth hormone for 3–4 days one had a marked reduction in pyruvate oxidation, while all had a decrease in glucose tolerance. Analysis of 14C in blood glucose at 60 minutes after injection of [2-14C]pyruvate suggested that slightly more total 14C-glucose was present in A2 than N1 without any differences between A2 and N2 or N1 and N2. Two out of 4 studies in A1 showed lower than normal amounts of 14Cglucose. No change in 14C-glucose occurred after administration of HGH. The findings suggest that impairment of pyruvate oxidation accompanies a lowered glucose tolerance in acromegalics with a diabetic tendency. Changes in gluconeogenesis from pyruvate appear to be minimal.