[Lactogenic effects of hyperinsulinemic-euglycaemic clamp in goats].

In the experiment performed on lactating goats, insulin was infused into the jugular vein over during 2 days every day at the rate 2 mg/kg/hour during 6 hour synchronously with glucose at variable rate to maintain euglycaemia; the transport activity (T, in clearance units) was estimated using the equation: T = Q x E/ (1-E), where Q is plasma flow and E is extraction efficiency. At the end of infusion of the 1st and 2nd days, insulin level in the blood was increased by 63 and 82%, mammary plasma flow by 38 and 78%, milk secretion rate by 23.7 and 31.

[Correlation between the organ blood flow, substrate absorption from blood, the activity of transport into mammary gland secretory cells and formation milk components in cow].

Epithelial cells of mammary alveoles may he considered as a bioreactor that works being monitored by regulatory system maintaining balance between blood substrate supply and rate of macromolecular synthesis. In the trial performed on lactating cows assigned to feeding regimen with temporally altered level of nutrition, functioning of this system in the course of a transition period was studied. The earliest sign of adaptation was a decrease in volume blood flow through mammary gland provoking decline in uptake of water soluble substrates (glucose, amino N, P-hydroxybutyrate) with increase in arterio-venous difference across mammary gland and extraction efficiency.