Regulation of bicarbonate secretion as fluid excretion in the salivary ducts

在本研究中，我们研究了卡巴胆碱(CCH)对腮腺小叶间管段管腔内荧光染料的排斥作用，以阐明腮腺小叶间管段与碳酸氢盐分泌的液体分泌能力。CCH在灌流荧光染料的过程中使管腔内的荧光强度降低，CCH可将染有荧光染料的细小粘性物质从离体管腔中排出。甲唑胺和外源性Ca~(2+)和Gt~(2+)的清除抑制CCH诱导的导管荧光清除。通过去除灌流液和DPC中的碳酸氢盐，大部分都能被抑制，但不能被低浓度的外部CT、布美他尼或DDS所抑制。斑块状观察表明存在钙激活的阴离子通道，而Granieidin穿孔斑片分析表明小苏打是分离的导管细胞外向电流的主要成分。这些结果提示，卡巴胆碱可能通过钙激活的、DPC敏感的阴离子通道和大鼠腮腺小叶内导管中HCO3+的分泌而产生液体分泌。

In the present study, we investigated the exclusion of fluorescent dye from the duct lumen by carbachol (CCh) in isolated parotid interlobular duct segments to clarify the ability of the ducts for the fluid secretion with bicarbonate secretion. CCh decreased the fluorescent intensity in the duct lumen during the superfusion of the fluorescent dye, and CCh flushed out small viscous substances stained with the fluorescent dye from isolated duct lumen. Methazolamide and removal of external Ca^<2+> suppressed CCh-induced clearance of the duct fluorescence. A major portion was inhibited by removal of bicarbonate in the superfusion solution and DPC, but not low concentration of external CT, bumetanide or DIDS. Patch-clump investigation indicated the presence of Ca^<2+> -activated anion channels, and gramieidin-perforated patched analysis indicated that bicarbonate was a major portion of outward currents in the isolated duct cells. These results suggest that carbachol evoles fluid secretion possibly through Ca^<2+> -activated, DPC-sensitive anion channels with HCO_3^- secretion in the rat parotid intralobular ducts.