Endotoxin of Escherichia coli and permeability of the mammary gland of goats.

Serial collections of milk were used to determine where in the mammary gland endotoxin of Escherichia coli was effective in altering the transfer of selected milk components into blood and blood components into milk. Lactating goats had half the gland infused with 1 microgram of endotoxin and the other half served as a control. Sodium-24 and 42K or [14C] lactose were included with 141Ce in the infusate in some experiments, whereas in others 99mTc-labelled albumin or 24Na and 42K were given intravenously 2 h after the endotoxin infusion. Milk was collected 3 h after endotoxin infusion. Endotoxin increased the loss of 24Na, 42K, and [14C] lactose from the mammary gland and increased the transfer of 24Na and 99mTc-albumin into the gland. The transfer in of 42K was reduced compared with control halves. Movement of stable Na and K was in accord with the movement of the 24Na and 42K. Endotoxin was effective in all parts of the gland but particularly from the mid-portion upward to the alveoli. For the control halves there was evidence that some 24Na and 42K crossed the ductal or cisternal epithelium into blood outside of the alveoli, whereas only 42K provided evidence for transfer from blood to milk in these same regions. There was no demonstrable transfer of lactose and albumin in regions other than the alveoli.