The role of the large-conductance voltage-dependent and calcium-activated potassium (BKCa) channels in the regulation of rat ductus arteriosus tone
The role of the large-conductance voltage-dependent and calcium-activated potassium (BKCa) channels in the regulation of rat ductus arteriosus tone
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DOI：
10.1007/s00380-010-0008-1
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发表时间：
2010-11-01
影响因子：
1.5
通讯作者：
Nakanishi, Toshio
中科院分区：
文献类型：
--
作者：
Sun, Fang;Hayama, Emiko;Nakanishi, Toshio
大电导电压依赖性和钙激活钾（BKCa）通道在调节动脉导管（DA）张力中的作用尚不清楚。本研究的目的是检查是否BKCa α和β亚基和BKCa电流存在于大鼠DA，以及是否BKCa通道参与O-2诱导的导管收缩。采用实时荧光定量PCR方法检测了早产（19 D）和成熟（21 D）大鼠胎儿和足月新生儿（NB）DA中BKCa α和β亚基转录物（mRNA）。BKCa α mRNA的量随着发育的进行而减少。免疫荧光染色显示，BKCa α和β 1蛋白在各年龄组的DA中膜均与α-平滑肌肌动蛋白（α-SMA）共定位。a亚基的蛋白质表达在成熟DA中最大，而β 1亚基的表达在所有三组中没有差异。用肌电描记仪记录不同条件下19 D和21 D导管张力。19 D导管环表现出较差的O-2敏感性，并且对BKCa抑制剂（paxilline）或激活剂（NS 1619）无反应。21 D导管环在O-2诱导下发生明显的收缩。在缺氧或充氧条件下，Paxilline均不增加21 D DA张力。NS 1619仅在氧合条件下扩张21 D DA。全细胞膜片钳记录的BKCa电流在21 D DA平滑肌细胞（SMCs）中最大。我们的研究表明，BKCa通道存在于DA，但不参与O-2诱导的导管收缩。BKCa通道的激活导致血管舒张预收缩DA的O-2诱导，可能表明一种方法来维持开放的DA出生后。
The role of large-conductance voltage-dependent and calcium-activated potassium (BKCa) channels in the regulation of ductus arteriosus (DA) tone is not clear. This study aimed to examine whether BKCa alpha and beta subunits and BKCa currents are present in the rat DA, as well as whether the BKCa channels are involved in O-2-induced ductal constriction. BKCa alpha and beta subunit transcripts (mRNAs) were detected in the DA from premature (19D) and mature (21D) rat fetuses and full-term neonates (NB) by quantitative real-time PCR. The amount of BKCa alpha mRNAs decreased with advancing development. beta 1 was the dominant beta subunit in the DA, and the amount of beta 1 mRNAs was greatest in the mature DA. Immunofluorescence staining showed that the majority of BKCa a and beta 1 proteins were colocated with alpha smooth muscle actin (alpha-SMA) in the tunica media of the DA in all age groups. The protein expression of the a subunit was greatest in the mature DA, while the expression of the beta 1 subunit did not differ among all three groups. The 19D and 21D ductus tensions were recorded under various conditions by myograph. The 19D ductus rings exhibited poor O-2 sensitivity and no response to BKCa inhibitor (paxilline) or activator (NS1619). The 21D ductus rings developed significant constriction induced by O-2. Paxilline did not increase the 21D DA tension under either hypoxic or oxygenated conditions. NS1619 dilated the 21D DA only under oxygenated conditions. The recorded BKCa currents were greatest in the 21D DA smooth muscle cells (SMCs) upon using a whole-cell patch clamp. Our study indicated that BKCa channels exist in the DA but are not involved in O-2-induced ductal constriction. Activation of BKCa channels led to vasodilatation in the preconstricted DA induced by O-2, possibly suggesting a way to maintain the patency of DA after birth.