Effect of retinoic acid on the contractile competence of vascular
smooth muscle.
Wright, G., S. Wang, G. Bailey, V. Reichenbecher, and G. L. Wright.
Departments of Biochemistry and Physiology, Marshall University
School of Medicine, 1542 Spring Valley Drive, Huntington, W.Va.
25704
APStracts 2:0437H, 1995.
Rat aortic rings cultured for 24 h in protein-free media showed a
significant reduction in the contractile response to potassium (-60%)
and to phorbol 12, 13-dibutyrate (-65%). The addition of plasma to
the media attenuated the loss in responsiveness and the
supplementation of the plasma containing media with all-trans
retinoic acid (RA) returned the response to potassium (85%) and
phorbol ester (135%) to near normal or supramaximal compared to fresh
tissue. Furthermore, the combined additions of plasma and RA resulted
in significant preservation of the contractile response (75%) for at
least 3 days in organ culture. Removal of the endothelium prior to
organ culture eliminated the enhancement of contraction by plasma and
RA. However, the removal of the endothelium from tissues that had
been cultured with an intact endothelium or the blockade of nitric
oxide synthesis in these tissues prior to contractile measurements
had no effect on the contractile response. Finally, the incubation of
tissues with phorbol ester to down-regulate protein kinase C (PKC)
resulted in a marked attenuation (-75%) of the contractile response
compared to control tissues in culture. The results suggest that
circulating factors may be necessary for the maintenance of
contractile function of aortic smooth muscle. Based on the opposing
actions of RA and phorbol ester, the long-term regulation of
contractile function may involve PKC activity.
Received 27 July 1995; accepted in final form 13 September 1995.
APS Manuscript Number H712-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95