Homeostasis of endolymph pH and Ca^<2+>

内淋巴是一种细胞外液，但它有一种独特的组成，即K^+含量高，Na^+、Ca^2+和gt；C l^-、HCO3^-主要以阴离子形式存在。由于内淋巴中几乎不含蛋白质、磷酸，因此认为HCO3-和CO2是内淋巴pH稳定的主要缓冲体系。本研究采用离子选择微电极在恒定呼吸条件下测定内淋巴pH，同时进行血气分析。内淋巴pH为7.5 9±0.108(平均±SD)(n=10)，血pH为7.5 7±0.067，血CO_2分压为22.6±2.44 mm Hg，血HCO3~-为19.8±2.45mEq/l，与内淋巴pH和血pH的相关系数为0.85。血CO_2分压与血HCO3~-呈负相关，血HCO3~-与内淋巴pH呈正相关，与血HCO3~-相关显著。内淋巴pH由HCO3~-/CO_2缓冲体系维持，不受血中CO_2分压的影响。HCO3~-在内耳的产生和转运机制与内液pH有关。有必要弄清楚内淋巴pH值的控制机制，进一步了解内耳的一般生理学和病理生理学

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