Activation of water-responsive laryngeal afferents: role of epithelial ion transport.
The role of epithelial ion transport in the activation of water-responsive laryngeal afferent was investigated in anesthetized, spontaneously breathing cats. Single-fiber recordings from the peripheral cut-end of the superior laryngeal nerve were carried out to identify water-responsive laryngeal afferent. Substitution of chloride ions (Cl-) of the Krebs solution with gluconate activated the water-responsive endings when the gluconate concentration was > or = 50 mM. Amiloride (10(-4), 10(-3) and 10(-2) M), an inhibitor of epithelial sodium channels, reduced the water-responsiveness of these afferents, whereas EIPA (5 x 10(-5) M), an amiloride analogue which inhibits Na+/H+ exchange, had no effect. Both ouabain (10(-4) M), an inhibitor of Na+/K+ ATPase, and bumetanide (10(-4) M), an inhibitor of Na(+)-K(+)-2Cl- cotransport, reduced the water response, but no significant reduction in the response was observed with DIDS and DPC, two chloride channel inhibitors. These findings suggest that the epithelium modulates the water-responsiveness of laryngeal afferent but is not the primary determinant of the response.
Ghosh
T K
TK
Department of Pediatrics, East Carolina University School of Medicine, Greenville, NC 27858, USA.
Van Scott
M R
MR
Mathew
O P
OP
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000344:Afferent Pathways / Q000378:metabolism; D000584:Amiloride / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D002034:Bumetanide / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002415:Cats; D018118:Chloride Channels / Q000037:antagonists & inhibitors; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004848:Epithelium / Q000187:drug effects / Q000294:innervation / Q000378:metabolism; D017136:Ion Transport / Q000187:drug effects; D007823:Laryngeal Nerves / Q000187:drug effects* / Q000378:metabolism*; D008954:Models, Biological; D010042:Ouabain / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors; D014867:Water / Q000494:pharmacology*; D062367:ortho-Aminobenzoates / Q000494:pharmacology
D002121:Calcium Channel Blockers; D018118:Chloride Channels; D004791:Enzyme Inhibitors; D062367:ortho-Aminobenzoates; D014867:Water; D002034:Bumetanide; D010042:Ouabain; D000584:Amiloride; C001209:fenamic acid; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; C039614:ethylisopropylamiloride