INSULIN-INDEPENDENT GLUCOSE-UPTAKE IN GROWTH-HORMONE TREATED DAIRY-COWS

Our aim was to determine the effect of growth hormone on non-insulin-m ediated glucose disposal in lactating dairy cows. Following 5 d of sub cutaneous injections of either saline or growth hormone, insulin, soma tostatin or insulin plus somatostatin were infused for 2 h each; in a series of experiments. Coincident with this, unlabelled glucose was in fused at a variable :rate to maintain a constant plasma glucose concen tration. Glucose, doubly labelled with deuterium, was also infused for the calculations of glucose turnover. Plasma insulin levels mere redu ced to nearly zero by the infusion of somatostatin; under such conditi ons whole body glucose disposal should be non-insulin-mediated. Dairy cows treated with growth hormone, which had significantly increased mi lk yields on the day before the experimental infusions. did not have d ifferent levels of whole body non-insulin-mediated glucose disposal wh en expressed in absolute terms. Growth hormone did not affect non mamm ary non-insulin-mediated glucose uptake estimated by calculation. Grow th hormone significantly inhibited insulin-mediated glucose uptake whe n plasma insulin levels were elevated. Glucose uptake during insulin p lus somatostatin infusion was not significantly different from that of the insulin only infusion.