Dynamic changes in gi[alpha]2 levels in the rat heart associated
with impaired cardiac function following acute myocardial
infarction.
Shi, Bing, James E. Heavner, Kathryn K. McMahon, Julian E. Spallholz,.
Food and Nutrition, Texas Tech University, and the Departments of
Anesthesiology, Physiology, and Pharmacology, Texas Tech University
Health Sciences Center, Lubbock, Texas 79430
APStracts 2:0151H, 1995.
The objective of this study was to determine if levels and function of
Gs[alpha] and Gia2 in rat hearts change over time following acute
myocardial infarction (MI) and if so, whether the changes in G
proteins are associated with changes in heart function. As compared
with sham-operated controls, Gia2 level of MI rats did not change at
day 1, increased by 64% at day 3 (p<0.01) and 55% at day 9
(p<0.05) accompanied by reduced adenylyl cyclase activity, and
returned to control by day 21. By contrast, Gs[alpha] level did not
change at any time. Cardiac function in MI animals was markedly
impaired at days 1, 3 and 9 as evidenced by substantial elevation in
LVEDP and reduction in + and - dp/dtmax, and partially restored at
day 21. Increased Gia2 level in MI rats correlated significantly to
severity of impaired cardiac function. The results show a three phase
dynamic pattern in Gia2 level following acute MI: a lag phase, an
increased expression phase associated with marked impairment of heart
function, and a late phase in which the expression returns to control
level accompanied by partially restored cardiac function.
Received 5 January 1995; accepted in final form 31 March 1995.
APS Manuscript Number H0007-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 19 April 1995.