AJP - Cell Physiology, Vol 234, Issue 5 177-C180, Copyright © 1978 by American Physiological Society
Inhibition of mammary gland lactose secretion by colchicine and vincristine
M. A. Guerin and R. F. Loizzi
The possible role of microtubules in milk production was examined in
mammary gland slices from lactating guinea pigs. Colchicine, 10(-5)-10(-4)
M, depressed lactose secretion within 15 min, maintaining maximal
inhibition over 2.5 h, accompanied by retention of lactose within the
slices. In colchicine dose-response studies (2 h, 10(-8)-10(-5) M),
secretion was depressed 22% by 10(-5) M, whereas tissue lactose increased
with dose up to +25% at 10(-5) M. Lactose synthesis was inhibited 3-19%
without correlation to colchicine concentration. In another study,
incubation with 10(-5) M lumicolchicine yielded one-third less inhibition
of secretion than 10(-5) M colchicine with no increase in tissue lactose.
Both drugs depressed synthesis 31%. Lactose secretion showed a negative
correlation with 10(-7)-10(-4) M vincristine yielding a maximal 66%
inhibition at 10(-4) M, whereas tissue retention showed a linear increase
with concentration up to 151% of control at 10(-4) M. Effects on synthesis
were sporadic. These data suggest that microtubules have a role in
facilitating the transport and/or secretion of lactose and perhaps other
milk components.
