Microtubule disruption stimulates system a transport in cultured
vascular smooth muscle cells.
Chen, Jie-Guang, Andrew B. Strawbridge, and Stephen A. Kempson.
Department of Physiology & Biophysics, Indiana University School of
Medicine, Indianapolis, IN 46202-5120
APStracts 2:0117C, 1995.
This study has focused on the possible influence of microtubules for
the regulation of Na+-dependent system A neutral amino acid transport
in A10 cells, a cultured cell line derived from rat aortic vascular
smooth muscle. When microtubules were disrupted by incubating cells
for 5 h in serum-free medium containing colchicine, nocodazole or
vinblastine, there was a two-fold increase in system A transport
(Vmax change). The dose for the disruption of microtubules by
colchicine was similar to the dose required for the stimulation of
system A. The time course showed that system A stimulation did not
occur until widespread disruption of microtubules was established.
The stimulation was specific for system A, there were no changes in
glucose transport and Na+-dependent transport of phosphate and
glutamate. Serum refeeding of quiescent cells from 2 days of serum
starvation led to stimulation of system A, glucose and phosphate
transport. However, only system A was activated when colchicine was
added to the serum-free medium. Addition of colchicine during serum
refeeding had no additive effect for the stimulation of system A. The
stimulation by both colchicine and serum was blocked by cycloheximide
and actinomycin D. These findings suggest that microtubule disruption
may activate system A gene expression.
Received 19 September 1994; accepted in final form 20 December
1994.
APS Manuscript Number C559-4.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 7 March 1995.