Involvement of apical P2Y2 receptor-regulated CFTR activity in muscarinic stimulation of Cl- reabsorption in rat submandibular gland
Involvement of apical P2Y2 receptor-regulated CFTR activity in muscarinic stimulation of Cl- reabsorption in rat submandibular gland
复制标题
DOI：
10.1152/ajpregu.00758.2007
复制
发表时间：
2008-05-01
影响因子：
2.8
通讯作者：
Yamazaki, Jun
中科院分区：
文献类型：
--
作者：
Ishibashi, Kazunari;Okamura, Kazuhiko;Yamazaki, Jun
在此之前，我们提出了在体内的证据cAMP调节的CFTR Cl-通道的生理意义的钙激活的Cl-重吸收在导管系统的大鼠下颌下腺。在这里，我们解决的机制，基础CFTR激活有助于跨上皮Cl-运动引起的毒蕈碱刺激。当将CFTR的小干扰RNA或特异性CFTR抑制剂CFTRinh-172逆行注射到腺体自身导管中时，毛果芸香碱刺激期间大鼠下颌下腺的最终唾液中的Cl-浓度（[Cl-]）增加，表明基础CFTR激活参与Cl-重吸收。全身给予普萘洛尔未能改变[Cl-]，表明通过基础CFTR激活发生的Cl-运动中β-肾上腺素能途径几乎没有参与。导管内注射苏拉明（一种非特异性P2受体拮抗剂）增加唾液[Cl-]，表明存在内源性嘌呤能激活。在单独导管内注射时，ATP和P2 Y（2）受体激动剂UTP几乎同等地降低唾液[Cl-]。CFTRinh-172和苏拉明都能阻止这些作用，而P2 X（7）激动剂2 '，3'-O-（4-苯甲酰基苯甲酰基）-ATP（Bz-ATP）没有特异性作用。毛果芸香碱刺激诱发ATP分泌到唾液中。免疫组化显示CFTR和P2 Y（2）受体部分共存于该腺体纹状管上皮细胞的管腔表面。这些结果提高了毒蕈碱刺激诱导的Cl-重吸收通过基础CFTR活性发生的可能性，并且这通过分泌到唾液中的ATP的刺激由导管上皮中的P2 Y（2）受体调节。
Previously, we presented in vivo evidence for a physiological significance of cAMP-regulated CFTR Cl- channels in Ca2+-activated Cl- reabsorption in the ductal system of the rat submandibular gland. Here, we address the mechanism by which basal CFTR activation contributes to the transepithelial Cl- movement evoked by muscarinic stimulation. The Cl- concentration ([Cl-]) was increased in the final saliva from rat submandibular gland during pilocarpine stimulation when a small interfering RNA for CFTR or a specific CFTR inhibitor, CFTRinh-172, was injected retrogradely into the gland's own duct, indicating that basal CFTR activation is involved in Cl- reabsorption. Systemically administered propranolol failed to alter the [Cl-], suggesting little involvement of a beta-adrenergic pathway in the Cl- movement that occurs through basal CFTR activation. Intraductal injection of suramin (a nonspecific P2-receptor antagonist) increased the salivary [Cl-], indicating the existence of endogenous purinergic activation. Upon separate intraductal injection, ATP and a P2Y(2)-receptor agonist, UTP, decreased the salivary [Cl-] almost equipotently. CFTRinh-172 and suramin each prevented these effects, whereas 2', 3'-O-(4-benzoylbenzoyl)-ATP (Bz-ATP), a P2X(7) agonist, had no specific effect. Pilocarpine stimulation evoked ATP secretion into the salivary fluid. Immunohistochemistry revealed the partial coexistence of CFTR and P2Y(2) receptors on the luminal surface of epithelial cells in the striated ducts of this gland. These results raise the possibility that muscarinic stimulation-induced Cl- reabsorption occurs through basal CFTR activity and that this is regulated by P2Y(2) receptors in the ductal epithelium via stimulation by ATP secreted into the salivary fluid.