Regulation of type ii adenylyl cyclase mrna in rabbit skeletal
muscle by chronic motor nerve pacing.
Torgan, Carol E., and William E. Kraus.
Department of Medicine, Division of Cardiology, Duke University
Medical Center, Durham, NC 27710
APStracts 3:0080E, 1996.
Skeletal muscle exhibits a wide range in functional phenotype in
response to changes in physiologic demands. We have observed that in
response to changes in work patterns, alterations in gene expression
of some proteins coincide with changes in adenylyl cyclase (AC)
activity (Kraus, W. E., et al. Am. J. Physiol:. 263 (Endocrinol.
Metab. 26): E266-E230, 1992). We now examine AC isoform transcript
prevalence in various rabbit skeletal muscles and in response to
changing work demands. Using reverse transcriptase-polymerase chain
reaction (RT-PCR), we detected type II AC isoform transcripts in
rabbit skeletal muscle. RNase protection analyses revealed that
expression of the type II isoform significantly correlated with the
percentage of fast-twitch, type IIb/IId fibers (r2 = 0.765,
p<0.01). When a fast-twitch muscle was converted to a slow
-twitch muscle via chronic electrical pacing, expression of type II AC
mRNA significantly decreased. This response occurred 3 days after the
onset of stimulation (78% decrease), and was still present after 21
days of stimulation (76% decrease). As type II AC is relatively
insensitive to calcium regulation while sensitive to PKC signaling,
these data provide further impetus for investigations of PKA and PKC
cross-talk signaling mechanisms in the regulation of gene expression.
Received 10 October 1995; accepted in final form 11 March 1996.
APS Manuscript Number E493-5.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 23 April 96