A unique myosin isoform transition in cat striated external anal
sphincter muscle induced by denervation.
Kustasz, Richard, William Helferich, Thomas Adams, and Jacob Krier.
Department of Physiology and Department of Food Science and Human
Nutrition, Michigan State University, East Lansing, Michigan 48824
-1101
APStracts 3:0183G, 1996.
Denervation of limb and trunk muscles leads to characteristic changes
in their biochemical properties. The effects of denervation in the
striated external anal sphincter muscle (EAS) have not been studied,
however, even though denervation is a common etiology for fecal
incontinence. The present study reports effects of denervation of the
cat EAS and compares them with changes in a denervated limb muscle
(cat extensor digitorum longus (EDL)). Nerves supplying the EAS and
the EDL were sectioned in anesthetized cats, which were allowed to
recover and survive for 10, 30, or 60 days. Their muscles were then
excised and myofibrillar proteins isolated. Myosin heavy chain (MHC)
isoform composition was measured by SDS-polyacrylamide gel
electrophoresis. The EDL and EAS showed progressive increases in MHC
type IIA and progressive decreases in MHC type IIB at 10, 30, and 60
days. MHC type I progressively increased in the EDL, but showed no
change in the EAS. We hypothesize that this distinctive transition is
related to the unique embryologic origin and function of the EAS.
Received 1 May 1996; accepted in final form 16 September 1996.
APS Manuscript Number G171-6.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 7 October 1996