Traynor T R, O'Grady S M
Department of Physiology, University of Minnesota, Minneapolis 55455, USA.
Am J Physiol. 1996 Mar;270(3 Pt 1):C859-65. doi: 10.1152/ajpcell.1996.270.3.C859.
The purpose of this study was to examine the potential modulatory effects of gastrin-releasing peptide (GRP) on prostaglandin (PG) E2-stimulated electrolyte transport across the distal colon epithelium. In an earlier study, PGE2 was shown to reduce net Cl absorption without altering the serosal-to-mucosal unidirectional Cl flux in porcine distal colon (19). In the present study, tissues were pretreated with serosal or mucosal GRP and subsequently stimulated with PGE2. The resulting increase in short-circuit current (ISC) was 152% (serosal GRP) and 49% (mucosal GRP) greater than control PGE2 responses alone. Serosal, but not mucosal, GRP also enhanced the ISC response to vasoactive intestinal peptide. On the basis of flux measurements, the combined effects of serosal GRP and PGE2 resulted in the activation of a transcellular pathway for Cl secretion, which was not activated by either mediator alone. The time course of the PGE2 response was also affected by GRP. Serosal GRP shortened the time to maximum ISC by 35%, whereas mucosal peptide lengthened the time to maximum ISC by 68% These results suggest that GRP acts as a modulator of PG action on electrolyte transport in the distal colon.
本研究的目的是检测胃泌素释放肽（GRP）对前列腺素（PG）E2刺激的远端结肠上皮电解质转运的潜在调节作用。在早期研究中，PGE2被证明可减少猪远端结肠的净氯吸收，而不改变从浆膜侧到黏膜侧的单向氯通量（19）。在本研究中，组织先用浆膜侧或黏膜侧的GRP进行预处理，随后用PGE2刺激。由此产生的短路电流（ISC）增加分别比单独的对照PGE2反应高152%（浆膜侧GRP）和49%（黏膜侧GRP）。浆膜侧而非黏膜侧的GRP还增强了对血管活性肠肽的ISC反应。基于通量测量，浆膜侧GRP和PGE2的联合作用导致了一条跨细胞氯分泌途径的激活，单独使用任何一种介质均未激活该途径。PGE2反应的时间进程也受到GRP的影响。浆膜侧GRP使达到最大ISC的时间缩短了35%，而黏膜侧肽使达到最大ISC的时间延长了68%。这些结果表明，GRP作为PG对远端结肠电解质转运作用的调节剂。
