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Toad skin sensory mechanisms: correlation between behavioral, neural and electrophysiological responses associated with water absorption.
Author(s) -
Hillyard Stanley D,
Willumsen Niels J
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.813.11
Subject(s) - osmotic concentration , chemistry , mannitol , biophysics , distilled water , electrophysiology , toad , depolarization , absorption (acoustics) , transepithelial potential difference , chromatography , membrane , biochemistry , medicine , endocrinology , biology , ion transporter , materials science , composite material
Dehydrated toads respond to ionic and osmotic properties of water in potential rehydration sources. Thus, when exposed to high NaCl concentrations (>125 mM) the time showing hydration behavior is significantly reduced relative to distilled water (DI). Similarly, hydration behavior time is strongly reduced when the animals are presented with hyperosmotic (500 mM) mannitol. Previous studies with intracellular microelectrodes indicated that exposure of the isolated skin epithelium to Ringer made hyperosmotic with 207 mM mannitol caused a depolarization of the basolateral membrane potential (Vb) of skin keratinocytes similar to that of 250 mM NaCl. Thus, Vb appears sensitive to osmotic as well as ionic stimuli. We investigated the afferent nerve activity of spinal nerve #6 when the ventral skin was exposed to DI water and hyperosmotic solutions known to reduce water absorption behavior. The data indicated that Ringer elicits a neural response significantly greater than DI but comparable to 250 mM NaCl while 500 mM NaCl elicited a substantially larger neural response. Interestingly, the neural responses to the same solutions were often amplified by pre‐treatment with 500 mM mannitol, significantly so with 500 mM NaCl. Our data indicate that the neural response associated with water absorption behavior is determined partly by ionic composition and partly by osmotic strength.