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Na(+)-independent Mg(2+) transport sensitive to 2-aminoethoxydiphenyl borate (2-APB) in vascular smooth muscle cells: involvement of TRPM-like channels.

Hamaguchi Y, Matsubara T, Amano T, Uetani T, Asano H, Iwamoto T, Furukawa K, Murohara T, Nakayama S - J. Cell. Mol. Med. (2008)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan.

ABSTRACT
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 approximately 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.

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RT-PCR detection of TRPM channel members in porcine carotid arteries. The PCR amplification was performed by 35 cycles. A 100-bp molecular weight marker was used (right column). The size of each PCR product is as expected from the mouse and human sequences.
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fig07: RT-PCR detection of TRPM channel members in porcine carotid arteries. The PCR amplification was performed by 35 cycles. A 100-bp molecular weight marker was used (right column). The size of each PCR product is as expected from the mouse and human sequences.

Mentions: TRPM6 and TRPM7 are known Mg2+-permeable non-selective cation channels. It has been shown that TRPM6 is abundant in the kidney and small intestine, while TRPM7 is expressed ubiquitously in numerous tissues and organs [9, 21, 22]. It is thought that the former and latter are responsible for Mg2+ regulation at the organ and cellular levels, respectively. In line with this notion, RT-PCR examinations revealed that TRPM7 was a major component of TRPM homologues in porcine carotid arteries, but TRPM6 was also detectable (Fig. 7). Previous patch clamp studies have shown that the removal of extracellular divalent cations facilitates TRPM7-like current [9, 11, 23], a finding that is in good agreement with our [Mg2+]i measurements, that is Figure 5.


Na(+)-independent Mg(2+) transport sensitive to 2-aminoethoxydiphenyl borate (2-APB) in vascular smooth muscle cells: involvement of TRPM-like channels.

Hamaguchi Y, Matsubara T, Amano T, Uetani T, Asano H, Iwamoto T, Furukawa K, Murohara T, Nakayama S - J. Cell. Mol. Med. (2008)

RT-PCR detection of TRPM channel members in porcine carotid arteries. The PCR amplification was performed by 35 cycles. A 100-bp molecular weight marker was used (right column). The size of each PCR product is as expected from the mouse and human sequences.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4401140&req=5

fig07: RT-PCR detection of TRPM channel members in porcine carotid arteries. The PCR amplification was performed by 35 cycles. A 100-bp molecular weight marker was used (right column). The size of each PCR product is as expected from the mouse and human sequences.
Mentions: TRPM6 and TRPM7 are known Mg2+-permeable non-selective cation channels. It has been shown that TRPM6 is abundant in the kidney and small intestine, while TRPM7 is expressed ubiquitously in numerous tissues and organs [9, 21, 22]. It is thought that the former and latter are responsible for Mg2+ regulation at the organ and cellular levels, respectively. In line with this notion, RT-PCR examinations revealed that TRPM7 was a major component of TRPM homologues in porcine carotid arteries, but TRPM6 was also detectable (Fig. 7). Previous patch clamp studies have shown that the removal of extracellular divalent cations facilitates TRPM7-like current [9, 11, 23], a finding that is in good agreement with our [Mg2+]i measurements, that is Figure 5.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan.

ABSTRACT
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 approximately 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.

Show MeSH
Related in: MedlinePlus