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Myometrial relaxation of mice via expression of two pore domain acid sensitive K + (TASK-2) channels

View Article: PubMed Central - PubMed

ABSTRACT

Myometrial relaxation of mouse via expression of two-pore domain acid sensitive (TASK) channels was studied. In our previous report, we suggested that two-pore domain acid-sensing K+ channels (TASK-2) might be one of the candidates for the regulation of uterine circular smooth muscles in mice. In this study, we tried to show the mechanisms of relaxation via TASK-2 channels in marine myometrium. Isometric contraction measurements and patch clamp technique were used to verify TASK conductance in murine myometrium. Western blot and immunehistochemical study under confocal microscopy were used to investigate molecular identity of TASK channel. In this study, we showed that TEA and 4-AP insensitive non-inactivating outward K+ current (NIOK) may be responsible for the quiescence of murine pregnant longitudinal myometrium. The characteristics of NIOK coincided with two-pore domain acid-sensing K+ channels (TASK-2). NIOK in the presence of K+ channel blockers was inhibited further by TASK inhibitors such as quinidine, bupivacaine, lidocaine, and extracellular acidosis. Furthermore, oxytocin and estrogen inhibited NIOK in pregnant myometrium. When compared to non-pregnant myometrium, pregnant myometrium showed stronger inhibition of NIOK by quinidine and increased immunohistochemical expression of TASK-2. Finally, TASK-2 inhibitors induced strong myometrial contraction even in the presence of L-methionine, a known inhibitor of stretch-activated channels in the longitudinal myometrium of mouse. Activation of TASK-2 channels seems to play an essential role for relaxing uterus during pregnancy and it might be one of the alternatives for preventing preterm delivery.

No MeSH data available.


Identification of TASK-2 by immunohistochemistry and Western blot in mouse myometrium.(A, B) Laser scanning confocal micrograph shows TASK-2 immunoreactivity on the membrane of a single pregnant cell. Confocal images at 2 µm intervals showed localization of the TASK-2 channel on the cell membrane of pregnant myometrial cells. Highly increased immunoreactivity for the TASK-2 antibody in single pregnant myometrial cells ws observed compared to that in non-pregnant cells. (C) TASK-2 was increased in pregnancy compared to the control under Western blot (595 vs 100, p<0.05; n=3 and 4).
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Figure 5: Identification of TASK-2 by immunohistochemistry and Western blot in mouse myometrium.(A, B) Laser scanning confocal micrograph shows TASK-2 immunoreactivity on the membrane of a single pregnant cell. Confocal images at 2 µm intervals showed localization of the TASK-2 channel on the cell membrane of pregnant myometrial cells. Highly increased immunoreactivity for the TASK-2 antibody in single pregnant myometrial cells ws observed compared to that in non-pregnant cells. (C) TASK-2 was increased in pregnancy compared to the control under Western blot (595 vs 100, p<0.05; n=3 and 4).

Mentions: The electrophysiology and mechanical findings led us to study TASK-2 channel expression. Confocal images at 2 µm intervals showed localization of the TASK-2 channel on the cell membrane of pregnant myometrial cells (Fig. 5A). As shown in Fig. 5B, we found highly increased immunoreactivity for the TASK-2 antibody in single pregnant myometrial cells compared to that in non-pregnant cells by confocal microscopy. The increased expression of TASK-2 in pregnancy compared to the control was also observed by Western blot (595±243.88 vs 100±19.61, p<0.05; n=3 and 4) (Fig. 5C). Although data not shown, TASK-1 was also expressed in mouse but not significantly different in two groups (data not shown). Meanwhile, TASK-3 was not expressed in murine myometrium under Western blot.


Myometrial relaxation of mice via expression of two pore domain acid sensitive K + (TASK-2) channels
Identification of TASK-2 by immunohistochemistry and Western blot in mouse myometrium.(A, B) Laser scanning confocal micrograph shows TASK-2 immunoreactivity on the membrane of a single pregnant cell. Confocal images at 2 µm intervals showed localization of the TASK-2 channel on the cell membrane of pregnant myometrial cells. Highly increased immunoreactivity for the TASK-2 antibody in single pregnant myometrial cells ws observed compared to that in non-pregnant cells. (C) TASK-2 was increased in pregnancy compared to the control under Western blot (595 vs 100, p<0.05; n=3 and 4).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5015002&req=5

Figure 5: Identification of TASK-2 by immunohistochemistry and Western blot in mouse myometrium.(A, B) Laser scanning confocal micrograph shows TASK-2 immunoreactivity on the membrane of a single pregnant cell. Confocal images at 2 µm intervals showed localization of the TASK-2 channel on the cell membrane of pregnant myometrial cells. Highly increased immunoreactivity for the TASK-2 antibody in single pregnant myometrial cells ws observed compared to that in non-pregnant cells. (C) TASK-2 was increased in pregnancy compared to the control under Western blot (595 vs 100, p<0.05; n=3 and 4).
Mentions: The electrophysiology and mechanical findings led us to study TASK-2 channel expression. Confocal images at 2 µm intervals showed localization of the TASK-2 channel on the cell membrane of pregnant myometrial cells (Fig. 5A). As shown in Fig. 5B, we found highly increased immunoreactivity for the TASK-2 antibody in single pregnant myometrial cells compared to that in non-pregnant cells by confocal microscopy. The increased expression of TASK-2 in pregnancy compared to the control was also observed by Western blot (595±243.88 vs 100±19.61, p<0.05; n=3 and 4) (Fig. 5C). Although data not shown, TASK-1 was also expressed in mouse but not significantly different in two groups (data not shown). Meanwhile, TASK-3 was not expressed in murine myometrium under Western blot.

View Article: PubMed Central - PubMed

ABSTRACT

Myometrial relaxation of mouse via expression of two-pore domain acid sensitive (TASK) channels was studied. In our previous report, we suggested that two-pore domain acid-sensing K+ channels (TASK-2) might be one of the candidates for the regulation of uterine circular smooth muscles in mice. In this study, we tried to show the mechanisms of relaxation via TASK-2 channels in marine myometrium. Isometric contraction measurements and patch clamp technique were used to verify TASK conductance in murine myometrium. Western blot and immunehistochemical study under confocal microscopy were used to investigate molecular identity of TASK channel. In this study, we showed that TEA and 4-AP insensitive non-inactivating outward K+ current (NIOK) may be responsible for the quiescence of murine pregnant longitudinal myometrium. The characteristics of NIOK coincided with two-pore domain acid-sensing K+ channels (TASK-2). NIOK in the presence of K+ channel blockers was inhibited further by TASK inhibitors such as quinidine, bupivacaine, lidocaine, and extracellular acidosis. Furthermore, oxytocin and estrogen inhibited NIOK in pregnant myometrium. When compared to non-pregnant myometrium, pregnant myometrium showed stronger inhibition of NIOK by quinidine and increased immunohistochemical expression of TASK-2. Finally, TASK-2 inhibitors induced strong myometrial contraction even in the presence of L-methionine, a known inhibitor of stretch-activated channels in the longitudinal myometrium of mouse. Activation of TASK-2 channels seems to play an essential role for relaxing uterus during pregnancy and it might be one of the alternatives for preventing preterm delivery.

No MeSH data available.