Open AccessNa + ‐independent Mg 2+ transport sensitive to 2‐aminoethoxydiphenyl borate (2‐APB) in vascular smooth muscle cells: involvement of TRPM‐like channels
Author(s) -
Hamaguchi Yukihisa,
Matsubara Tatsuaki,
Amano Tetsuya,
Uetani Tadayuki,
Asano Haruhiko,
Iwamoto Takashi,
Furukawa Koichi,
Murohara Toyoaki,
Nakayama Shinsuke
Publication year - 2008
Publication title -
journal of cellular and molecular medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.44
H-Index - 130
eISSN - 1582-4934
pISSN - 1582-1838
DOI - 10.1111/j.1582-4934.2008.00157.x
Subject(s) - extracellular , intracellular , chemistry , divalent , vascular smooth muscle , homeostasis , biophysics , magnesium , medicine , biochemistry , endocrinology , smooth muscle , biology , organic chemistry
Magnesium is associated with several important cardiovascular diseases. There is an accumulating body of evidence verifying the important roles of Mg 2+ ‐permeable channels. In the present study, we estimated the intracellular free Mg 2+ concentration ([Mg 2+ ] i ) using 31 P‐nuclear magnetic resonance ( 31 P‐NMR) in porcine carotid arteries. pH i and intracellular phosphorus compounds were simultaneously monitored. Removal of extracellular divalent cations (Ca 2+ and Mg 2+ ) in the absence of Na + caused a gradual decrease in [Mg 2+ ] i to ∼60% of the control value after 125 min. On the other hand, the simultaneous removal of extracellular Ca 2+ and Na + in the presence of Mg 2+ gradually increased [Mg 2+ ] i in an extracellular Mg 2+ ‐dependent manner. 2‐aminoethoxydiphenyl borate (2‐APB) attenuated both [Mg 2+ ] i load and depletion caused under Na + ‐ and Ca 2+ ‐free conditions. Neither [ATP] i nor pH i correlated with changes in [Mg 2+ ] i . RT‐PCR detected transcripts of both TRPM6 and TRPM7, although TRPM7 was predominant. In conclusion, the results suggest the presence of Mg 2+ ‐permeable channels of TRPM family that contribute to Mg 2+ homeostasis in vascular smooth muscle cells. The low, basal [Mg 2+ ] i level in vascular smooth muscle cells is attributable to the relatively low activity of this Mg 2+ entry pathway.