Effect of locally applied drugs on the pH of luminal fluid in the endolymphatic sac of guinea pig.
The aim of the present work was to assess the effect of various drugs applied locally on the pH of the luminal fluid (pH(lum)) in guinea pig endolymphatic sac. pH(lum) and transepithelial potential, when measured in vivo by means of double-barrelled pH-sensitive microelectrodes, were 7.06 +/- 0.08 and +6.1 +/- 0.34 mV (mean +/- SE; n = 84), respectively, which is consistent with a net acid secretion in the luminal fluid of the endolymphatic sac. Bafilomycin and acetazolamide increased and decreased, respectively, pH(lum). Amiloride, ethylisopropylamiloride, ouabain, and Schering 28080 had no effect on pH(lum). Results obtained with inhibitors of anionic transport systems were inconclusive; e.g., DIDS reduced pH(lum), whereas neither SITS nor triflocin had any effect. We conclude that bafilomycin-sensitive H(+)-ATPase activity accounts for the transepithelial acid gradient measured in the endolymphatic sac and that intracellular and membrane-bound carbonic anhydrase probably participates in regulating endolymphatic sac pH(lum). The relationship between acid pH, endolymph volume, and Ménière's disease remains to be further investigated.
Couloigner
V
V
Institut National de la Santé et de la Recherche Médicale U.426, Faculté Xavier Bichat, Université Paris 7, 75870 Paris Cedex 18, France.
Teixeira
M
M
Hulin
P
P
Sterkers
O
O
Bichara
M
M
Escoubet
B
B
Planelles
G
G
Ferrary
E
E
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000086:Acetazolamide / Q000494:pharmacology; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001826:Body Fluids / Q000737:chemistry*; D002257:Carbonic Anhydrase Inhibitors / Q000494:pharmacology; D004712:Endolymphatic Sac / Q000187:drug effects* / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004848:Epithelium / Q000502:physiology; D006168:Guinea Pigs; D006863:Hydrogen-Ion Concentration; D007093:Imidazoles / Q000494:pharmacology; D018942:Macrolides; D008297:Male; D008564:Membrane Potentials; D008839:Microelectrodes; D010042:Ouabain / Q000494:pharmacology; D054328:Proton Pump Inhibitors; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers / Q000037:antagonists & inhibitors; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors
D000900:Anti-Bacterial Agents; D002257:Carbonic Anhydrase Inhibitors; D004791:Enzyme Inhibitors; D007093:Imidazoles; D018942:Macrolides; D054328:Proton Pump Inhibitors; D017923:Sodium-Hydrogen Exchangers; C035235:Sch 28080; C057620:bafilomycin A; D010042:Ouabain; D006180:Proton-Translocating ATPases; D000254:Sodium-Potassium-Exchanging ATPase; D000086:Acetazolamide; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid