کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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1974311 | 1060348 | 2006 | 13 صفحه PDF | دانلود رایگان |

The aim of the present study was to assess the cellular mechanism of secretion in the salivary gland of the snail, Helix pomatia, using electrophysiological, electron microscopic and immunohistochemical techniques. A homogeneously distributed membrane potential (− 56.6 ± 9.8 mV) was determined mainly by a K+-electrochemical gradient and partly by the contribution of the electrogenic Na+-pump and Cl− conductance. Low resistance electrical coupling sites were identified physiologically. Transmission electron microscopy and innexin 2 antibody revealed the presence of gap–junction-like membrane structures between gland cells. It is suggested that gap–junctions are sites of electrotonic intercellular communication, which integrate the gland cells into a synchronized functional unit in the acinus. Stimulation of the salivary nerve elicited secretory potentials (depolarization) which could be mimicked by local application of acetylcholine, dopamine or serotonin. In voltage-clamp experiments four major conductances were identified: a delayed rectifier (IK), a transient (IA) and a Ca2+-activated outward K+ current (IK(Ca)) and Ca2+-inward currents (ICa). It is suggested that one or more of these conductances may give rise to a stimulus activated secretory potential leading to excitation–secretion coupling and subsequent the release of the mucus from the gland cells.
Journal: Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology - Volume 145, Issue 1, September 2006, Pages 7–19