Severe dietary magnesium deficiency does not alter levels and
function of myocardial gs[alpha] and gi[alpha].
Shi, Bing, James E. Heavner, Julian E. Spallholz, L. Mallory Boylan.
The Departments of Anesthesiology and Physiology, Texas Tech
University Health Sciences Center, Food and Nutrition, Texas Tech
University, Lubbock, Texas 79430
APStracts 3:0166A, 1996.
Magnesium ions (Mg++) play a crucial role in the activation and
synthesis of guanine nucleotide-binding proteins (G proteins).
However, there is no information about the influence of in vivo Mg
deficiency on the function and levels of G proteins. This study was
done to investigate whether dietary Mg deficiency alters function and
levels of the two major myocardial G proteins, Gi[alpha] and
Gs[alpha]. Severe hypomagnesemia and a significant reduction of
myocardial Mg occurred in rats fed a Mg-deficient diet for 6 weeks
vs. rats fed a normal Mg diet (control). The Mg-deficient rats
developed focal myocardial lesions but their cardiac function was not
impaired. Myocardial immunodetectable Gs[alpha] and Gi[alpha] levels
of Mg-deficient rats did not differ from control (Gs[alpha]: 2.39+/
-0.52 vs. 2.76+/-0.72, p>0.05; Gi[alpha]: 1.60+/-0.52 vs. 1.89+/
-0.30 arbitrary units/[mu]g protein, p>0.05). Similarly, the
function of Gs[alpha] and Gi[alpha] estimated by basal and ligand
-stimulated adenylyl cyclase activity was not significantly different
between the two groups of animals. The results show that dietary
-derived Mg deficiency sufficient to produce severe hypomagnesemia
does not produce any significant change in levels or function of
myocardial G proteins.
Received 29 September 1995; accepted in final form 14 February
1996.
APS Manuscript Number A1056-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 1 April 96