Mechanism of Relaxation Via TASK-2 Channels in Uterine Circular Muscle of Mouse.
Plasma pH can be altered during pregnancy and at labor. Membrane excitability of smooth muscle including uterine muscle is suppressed by the activation of K(+) channels. Because contractility of uterine muscle is regulated by extracellular pH and humoral factors, K(+) conductance could be connected to factors regulating uterine contractility during pregnancy. Here, we showed that TASK-2 inhibitors such as quinidine, lidocaine, and extracellular acidosis produced contraction in uterine circular muscle of mouse. Furthermore, contractility was significantly increased in pregnant uterine circular muscle than that of non-pregnant muscle. These patterns were not changed even in the presence of tetraetylammonium (TEA) and 4-aminopyridine (4-AP). Finally, TASK-2 inhibitors induced strong myometrial contraction even in the presence of L-methionine, a known inhibitor of stretchactivated channels in myometrium. When compared to non-pregnant myometrium, pregnant myometrium showed increased immunohistochemical expression of TASK-2. Therefore, TASK-2, seems to play a key role during regulation of myometrial contractility in the pregnancy and provides new insight into preventing preterm delivery.
Department of Obstetrics and Gynecology, Chungbuk National University College of Medicine, Cheongju 361-763, Korea.
Seung Hwa
SH
Hong
Rohyun
R
Sung
Young Chul
YC
Kim
Hikaru
H
Suzuki
Woong
W
Choi
Yeon Jin
YJ
Park
Ill Woon
IW
Ji
Chan Hyung
CH
Kim
Sun Chul
SC
Myung
Moo Yeol
MY
Lee
Tong Mook
TM
Kang
Ra Young
RY
You
Kwang Ju
KJ
Lee
Seung Woon
SW
Lim
Hyo-Yung
HY
Yun
Young-Jin
YJ
Song
Wen-Xie
WX
Xu
Hak Soon
HS
Kim
Sang Jin
SJ
Lee
Relaxation; TASK-2; Uterus