Insulin secretion in lactating cows: responses to glucose infused intravenously in normal, ketonemic, and starved animals.
Changes in insulin concentrations of blood plasma were studied in lactating cows during and after a 1-h intravenous glucose infusion in 5 spontaneously ketonemic, 10 nonketonemic (normal), and 4 starved cows. A biphasic increase in insulin with a maximum 10 to 20 min after the start of the glucose infusion was followed by a sustained (1 to 2 h) elevation in the normal and ketonemic animals. In starved cows only the later phase was detectable. Insulin was higher in normal than in starved and ketonemic cows during both phases of the insulin secretion in spite of approximately identical glucose. Differences between starved and ketonemic cows were not major. Average rates of decline in sugar concentrations after the end of the infusion were higher in normal and ketonemic [half times 143 +/- 23 (standard deviation) and 166 +/- 22 min] than in starved cows (281 +/- 47 min). The low basal insulin of plasma and poor responses of insulin secretion following glucose infusions indicate sluggish beta-cell function in ketonemic cows.
D000090:Acetoacetates / Q000097:blood; D000138:Acidosis / Q000378:metabolism*; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002417:Cattle; D005260:Female; D005947:Glucose; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000503:physiopathology; D007662:Ketosis / Q000378:metabolism*; D007774:Lactation / Q000187:drug effects*; D011247:Pregnancy; D013217:Starvation / Q000378:metabolism*
D000090:Acetoacetates; D001786:Blood Glucose; D007328:Insulin; D005947:Glucose