title: Electrical properties and cell-to-cell communication of the salivary gland cells of the snail, Helix pomatia.
abstract: 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.
authors.affiliation: Department of Experimental Zoology, Balaton Limnological Research Institute, Hungarian Academy of Sciences, Tihany, 8237, Klebelsberg K. u. 3., Hungary.
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Pirger
authors.forename: Károly
authors.initials: K
authors.lastname: Elekes
authors.forename: Tibor
authors.initials: T
authors.lastname: Kiss
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002450:Cell Communication / Q000502:physiology*; D017630:Connexins / Q000032:analysis; D004298:Dopamine / Q000494:pharmacology; D017629:Gap Junctions / Q000737:chemistry / Q000378:metabolism; D006372:Helix, Snails / Q000166:cytology / Q000502:physiology*; D007150:Immunohistochemistry; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D046529:Microscopy, Electron, Transmission; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D018408:Patch-Clamp Techniques; D012469:Salivary Glands / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure; D012701:Serotonin / Q000494:pharmacology
chemical_list: D017630:Connexins; D012701:Serotonin; D000109:Acetylcholine; D004298:Dopamine