Endolymph is extracellular-fluid, but it has a unique composition where K^+ is high and Na^+, Ca^<2+> are low. Cl^-, HCO_3^- exist in as the main anion. It thinks that the HCO_3^- and CO_2 are working as the main buffer-system with the endolymph pH stabilization because proteins, phosphoric acids are hardly contained in the endolymph.
In the research this time, the endolymph pH was measured using the ion-selective microelectrode under constant breathing condition, and blood-gas-analysis at the same time. The endolymph pH was 7.59±0.108 (average±SD)(n=10), the blood-pH was 7.57±0.067, the blood CO_2 partial pressure was 22.6±2.44 mmHg and blood HCO_3^- was 19.8±2.45mEq/1. The coefficient of correlation with endolymph pH and blood-pH was 0.85. The blood CO_2 partial pressure had negative corr-elation, the blood HCO_3^- had a positive corr-elation with the endolymph pH, and the corr-elation with blood HCO_3^- was significant. Endolymph pH was maintained by HCO_3^-/CO_2 buffer-system, it wasn't fixed only by the blood CO_2 partial pressure. The production and transport-mechanism of HCO_3^- in the inner ear will participated in endolyph pH. it is necessary to make the controlling mechanism of the endolymph pH clear more understanding a inner ear general physiology and pathophysiology