Chemosensory function of salt and water transport by the amphibian skin

Solute and water transport mechanisms of anuran skin mediate chemosensory functions that permit evaluation of ionic and osmotic properties of hydration sources in a manner similar to taste receptors in the mammalian tongue. Histochemical observations demonstrated apparent connections between spinal...

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Bibliographic Details
Published in:Comparative biochemistry and physiology. Part A, Molecular & integrative physiology Molecular & integrative physiology, 2007-09, Vol.148 (1), p.44-54
Main Authors: Hillyard, Stanley D., Viborg, A., Nagai, T., Hoff, K.vS
Format: Article
Language:English
Subjects:
Amphibia
Amphibians
Animals
Anura
Biological Transport
Bufonidae - physiology
Chemosensation
Na + transport
Potassium Chloride - metabolism
Skin Physiological Phenomena
Sodium Chloride - metabolism
Water balance
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Summary:Solute and water transport mechanisms of anuran skin mediate chemosensory functions that permit evaluation of ionic and osmotic properties of hydration sources in a manner similar to taste receptors in the mammalian tongue. Histochemical observations demonstrated apparent connections between spinal nerve endings and epithelial cells of the skin and we used neural and behavioral responses as measures of coupling between transport and chemosensation. The inhibition of transcellular Na + transport by amiloride partially reduced the neural response and the avoidance of hyperosmotic NaCl but not KCl solutions. Cetylpyridinium chloride (CPC) reduced the neural response to hyperosmotic salt solutions, suggesting a chemosensory role for vanilloid receptors in the skin. Avoidance of hyperosmotic salt solutions was reduced by impermeant anions suggesting paracellular conductance is important for chemosensation. The effects of blocking the transcellular and paracellular pathways was additive but did not eliminate the avoidance of osmotically unfavorable solutions by dehydrated toads. The timing of the neural response to deionized water was similar to the onset of water absorption behavior and increased blood flow to the pelvic skin. Water absorption from 50 mM NaCl was greater than from deionized water when toads were fully immersed, but not when contact was limited to the ventral surface.
ISSN:1095-6433
1531-4332
DOI:10.1016/j.cbpa.2006.12.025