[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. At the end of deprivation period, an activity of transport into the cell decreased for amino N from 7.5 to 4.5; l/min (p < 0.05), for P-hydroxyhutyrate from 16.0 to 13.8 l/min; activity of glucose transport was not changed. The data obtained indicate existence of defined points in the system monitoring organ blood supply and transport of substrates into the cell being adjusted during adaptation to alteration in the level of nutrition.