ACIDOSIS EFFECTS ON INSULIN-RESPONSE DURING GLUCOSE-TOLERANCE TESTS IN JERSEY COWS

The effect of metabolic alkalosis and acidosis on insulin response to glucose tolerance tests was determined for cows fed a high cation diet to induce a state of metabolic alkalosis or a high anion diet to indu ce a state of metabolic acidosis. The glucose tolerance test (500 mg o f glucose/kg of BW infused i.v. over 10 min) caused a rapid increase i n plasma glucose and insulin concentrations. Plasma glucose concentrat ions were highest, and plasma insulin concentrations were lowest, duri ng metabolic acidosis. These results suggest that insulin secretion is impaired during metabolic acidosis, which may reduce tissue uptake of glucose. Correction of metabolic acidosis by oral administration of s odium bicarbonate prior to glucose tolerance testing increased blood p H and bicarbonate concentrations and partially restored insulin respon se to the glucose tolerance test. Interestingly, sodium bicarbonate al so caused an elevation in plasma cortisol concentrations. We concluded that glucose utilization is altered in cows with metabolic acidosis. The correction of acidosis associated with diseases such as diarrhea a nd ketosis may improve the therapeutic benefit of glucose infusions us ed to treat these diseases.