Martin S C, Shuttleworth T J
Department of Physiology, University of Rochester School of Medicine and Dentistry, NY 14642.
Regul Pept. 1994 Aug 4;52(3):205-14. doi: 10.1016/0167-0115(94)90055-8.
VIP plays an integral role in both protein and fluid secretion in many exocrine glands. By employing the perforated patch-clamp whole-cell recording technique we investigated the effects of VIP on membrane potential and transmembrane currents in avian exocrine salt gland cells. Prior to application of VIP, salt gland cells had a resting membrane potential close to -45 mV. When challenged with VIP (1-100 nM) a sustained depolarization to ECl- was induced which was mimicked by the application of cell-permeable cAMP analogues or forskolin (1 microM). By employing the voltage-clamp recording configuration a sustained increase in current was observed with a reversal potential which approximated ECl-. Ionic substitution experiments confirmed that the current was a Cl- conductance which was inhibited by the Cl- channel blockers flufenamic acid and niflumic acid and by the inhibitory cAMP isomer, adenosine-3',5'-cyclic monophosphothioate, Rp-isomer. Based on this, and the fact that the kinetic properties of the Cl- current activated by VIP are similar to those activated by cAMP, we propose that VIP-receptor interaction results in the activation of a cAMP-dependent Cl- current.
血管活性肠肽（VIP）在许多外分泌腺的蛋白质和液体分泌中发挥着不可或缺的作用。通过采用穿孔膜片钳全细胞记录技术，我们研究了VIP对鸟类外分泌盐腺细胞的膜电位和跨膜电流的影响。在施加VIP之前，盐腺细胞的静息膜电位接近-45 mV。当用VIP（1-100 nM）刺激时，会诱导出持续去极化至氯离子平衡电位（ECl-），这可被应用细胞可渗透的环磷酸腺苷（cAMP）类似物或福斯可林（1 microM）模拟。通过采用电压钳记录配置，观察到电流持续增加，其反转电位接近ECl-。离子替代实验证实该电流是一种氯离子电导，可被氯离子通道阻滞剂氟芬那酸和尼氟酸以及抑制性cAMP异构体3',5'-环磷腺苷单硫酯（Rp-异构体）抑制。基于此，以及VIP激活的氯离子电流的动力学特性与cAMP激活的氯离子电流相似这一事实，我们提出VIP与受体的相互作用导致了一种cAMP依赖性氯离子电流的激活。
