Insulin Secretion in Lactating Cows: Responses to Glucose Infused Intravenously in Normal, Ketonemic, and Starved Animals

Open Access
Publisher Website
Google Scholar
Abstract
Changes in insulin concentrations of blood plasma were studied in lactating cows during and after a 1 h i.v. glucose infusion in 5 spontaneously ketonemic, 10 nonketonemic (normal) and 4 starved cows. A biphasic increase in insulin 10-20 min after the start of glucose infusion was followed by a sustained (1-2 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 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.