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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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Correlation between [ATP]i and [Mg2+]i in the absence (0 Mg2+; A) and presence of extracellular Mg2+ (6 mM Mg2+; B). Each open () and filled circle () represents a 31P-NMR data point (spectrum accumulated over 25 min) obtained in the absence and presence of 2-APB, respectively. [ATP]i is expressed relative to that in the control. Data points in (A) are from experiments shown in Fig. 3, while those in (B) are from Fig. 5A.
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fig06: Correlation between [ATP]i and [Mg2+]i in the absence (0 Mg2+; A) and presence of extracellular Mg2+ (6 mM Mg2+; B). Each open () and filled circle () represents a 31P-NMR data point (spectrum accumulated over 25 min) obtained in the absence and presence of 2-APB, respectively. [ATP]i is expressed relative to that in the control. Data points in (A) are from experiments shown in Fig. 3, while those in (B) are from Fig. 5A.

Mentions: ATP is known to affect the activity of TRPM7 and to act as an important intracellular Mg2+ buffer. Correlation analysis revealed that [ATP]i and [Mg2+]i are not correlated regardless of the presence of extracellular Mg2+ (Fig. 6). Also, [PCr]i did not change significantly throughout (Supplementary Table S1).


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)

Correlation between [ATP]i and [Mg2+]i in the absence (0 Mg2+; A) and presence of extracellular Mg2+ (6 mM Mg2+; B). Each open () and filled circle () represents a 31P-NMR data point (spectrum accumulated over 25 min) obtained in the absence and presence of 2-APB, respectively. [ATP]i is expressed relative to that in the control. Data points in (A) are from experiments shown in Fig. 3, while those in (B) are from Fig. 5A.
© Copyright Policy
Related In: Results  -  Collection

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

fig06: Correlation between [ATP]i and [Mg2+]i in the absence (0 Mg2+; A) and presence of extracellular Mg2+ (6 mM Mg2+; B). Each open () and filled circle () represents a 31P-NMR data point (spectrum accumulated over 25 min) obtained in the absence and presence of 2-APB, respectively. [ATP]i is expressed relative to that in the control. Data points in (A) are from experiments shown in Fig. 3, while those in (B) are from Fig. 5A.
Mentions: ATP is known to affect the activity of TRPM7 and to act as an important intracellular Mg2+ buffer. Correlation analysis revealed that [ATP]i and [Mg2+]i are not correlated regardless of the presence of extracellular Mg2+ (Fig. 6). Also, [PCr]i did not change significantly throughout (Supplementary Table S1).

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