Severe dietary magnesium deficiency does not alter levels and function of myocardial Gs alpha and Gi alpha.
Magnesium ions (Mg2+) 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 magnesium deficiency on the function and levels of G proteins. This study was done to investigate whether dietary magnesium 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 magnesium occurred in rats fed a magnesium-deficient diet for 6 wk vs. rats fed a normal-magnesium diet (control). The magnesium-deficient rats developed focal myocardial lesions but their cardiac function was not impaired. Myocardial immunodetectable Gs alpha and Gi alpha levels of magnesium-deficient rats did not differ from control (Gs alpha: 2.39 +/- 0.52 vs. 2.76 +/- 0.72 arbitrary units/microgram protein, P > 0.05; Gi alpha: 1.60 +/- 0.52 vs. 1.89 +/- 0.30 arbitrary units/microgram 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 magnesium deficiency sufficient to produce severe hypomagnesemia does not produce any significant change in levels or function of myocardial G proteins.
Shi
B
B
Department of Anesthesiology, Texas Tech University Health Sciences Center, Texas Tech University, Lubbock 79430, USA.
Heavner
J E
JE
Spallholz
J E
JE
Boylan
L M
LM
D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D001835:Body Weight / Q000502:physiology; D002118:Calcium / Q000378:metabolism; D000242:Cyclic AMP / Q000096:biosynthesis; D004032:Diet; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism* / Q000502:physiology; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000378:metabolism* / Q000502:physiology; D006352:Heart Ventricles / Q000201:enzymology / Q000378:metabolism; D006439:Hemodynamics / Q000502:physiology; D015151:Immunoblotting; D008274:Magnesium / Q000378:metabolism; D008275:Magnesium Deficiency / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D008297:Male; D009206:Myocardium / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D011188:Potassium / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
D000242:Cyclic AMP; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D019205:GTP-Binding Protein alpha Subunits, Gs; D000262:Adenylyl Cyclases; D008274:Magnesium; D011188:Potassium; D002118:Calcium