Magnesium homeostasis in cardiac myocytes of Mg-deficient rats

• Published in: PloS one Vol. 8; no. 9; p. e73171
• Main Authors: Tashiro, Michiko, Inoue, Hana, Konishi, Masato
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 09.09.2013; Public Library of Science (PLoS)
• Subjects: Absorption spectroscopy; Animal tissues; Animals; Atomic absorption analysis; Atomic absorption spectroscopy; Atomic beam spectroscopy; Biological Transport; Body Weight; Cardiac muscle; Cardiomyocytes; Cation Transport Proteins - genetics; Cation Transport Proteins - metabolism; Cell Membrane - metabolism; Channels; Diet; Efflux; Extracellular Space - metabolism; Fluorescence; Gene Expression; Genomics; Heart; Heart diseases; Heart Ventricles - metabolism; Homeostasis; Hypomagnesemia; Kidneys; Magnesium; Magnesium - blood; Magnesium - metabolism; Magnesium Deficiency - genetics; Magnesium Deficiency - metabolism; Male; Minerals - blood; Minerals - metabolism; Modulation; Myocytes; Myocytes, Cardiac - metabolism; Physiology; Polymerase chain reaction; Proteins; Rats; RNA; Rodents; Spectral analysis; Spectroscopy; Spectrum analysis; Transient receptor potential proteins; Transport; Ventricle
• DOI: 10.1371/journal.pone.0073171
• ISSN: 1932-6203

To study possible modulation of Mg(2+) transport in low Mg(2+) conditions, we fed either a Mg-deficient diet or a Mg-containing diet (control) to Wistar rats for 1-6 weeks. Total Mg concentrations in serum and cardiac ventricular tissues were measured by atomic absorption spectroscopy. Intracellular free Mg(2+) concentration ([Mg(2+)]i) of ventricular myocytes was measured with the fluorescent indicator furaptra. Mg(2+) transport rates, rates of Mg(2+) influx and Mg(2+) efflux, were estimated from the rates of change in [Mg(2+)]i during Mg loading/depletion and recovery procedures. In Mg-deficient rats, the serum total Mg concentration (0.29±0.026 mM) was significantly lower than in control rats (0.86±0.072 mM) after 4-6 weeks of Mg deficiency. However, neither total Mg concentration in ventricular tissues nor [Mg(2+)]i of ventricular myocytes was significantly different between Mg-deficient rats and control rats. The rates of Mg(2+) influx and efflux were not significantly different in both groups. In addition, quantitative RT-PCR revealed that Mg deficiency did not substantially change mRNA expression levels of known Mg(2+) channels/transporters (TRPM6, TRPM7, MagT1, SLC41A1 and ACDP2) in heart and kidney tissues. These results suggest that [Mg(2+)]i as well as the total Mg content of cardiac myocytes, was well maintained even under chronic hypomagnesemia without persistent modulation in function and expression of major Mg(2+) channels/transporters in the heart.