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The gastric H,K-ATPase in stria vascularis contributes to pH regulation of cochlear endolymph but not to K secretion.
BMC Physiol 2016; 17(1):1BP

Abstract

BACKGROUND

Disturbance of acid-base balance in the inner ear is known to be associated with hearing loss in a number of conditions including genetic mutations and pharmacologic interventions. Several previous physiologic and immunohistochemical observations lead to proposals of the involvement of acid-base transporters in stria vascularis.

RESULTS

We directly measured acid flux in vitro from the apical side of isolated stria vascularis from adult C57Bl/6 mice with a novel constant-perfusion pH-selective self-referencing probe. Acid efflux that depended on metabolism and ion transport was observed from the apical side of stria vascularis. The acid flux was decreased to about 40 % of control by removal of the metabolic substrate (glucose-free) and by inhibition of the sodium pump (ouabain). The flux was also decreased a) by inhibition of Na,H-exchangers by amiloride, dimethylamiloride (DMA), S3226 and Hoe694, b) by inhibition of Na,2Cl,K-cotransporter (NKCC1) by bumetanide, and c) by the likely inhibition of HCO3/anion exchange by DIDS. By contrast, the acid flux was increased by inhibition of gastric H,K-ATPase (SCH28080) but was not affected by an inhibitor of vH-ATPase (bafilomycin).  K flux from stria vascularis was reduced less than 5 % by SCH28080.

CONCLUSIONS

These observations suggest that stria vascularis may be an important site of control of cochlear acid-base balance and demonstrate a functional role of several acid-base transporters in stria vascularis, including basolateral H,K-ATPase and apical Na,H-exchange. Previous suggestions that H secretion is mediated by an apical vH-ATPase and that basolateral H,K-ATPase contributes importantly to K secretion in stria vascularis are not supported. These results advance our understanding of inner ear acid-base balance and provide a stronger basis to interpret the etiology of genetic and pharmacologic cochlear dysfunctions that are influenced by endolymphatic pH.

Authors+Show Affiliations

Department of Anatomy & Physiology, Cellular Biophysics Laboratory, Kansas State University, 228 Coles Hall, Manhattan, KS, 66506-5802, USA. Deparment of Anatomy & Physiology, Cell Physiology Laboratory, Kansas State University, 228 Coles Hall, Manhattan, KS 66506-5802, USA. Department of Otolaryngology-Head and Neck Surgery, Tohoku University Graduate School of Medicine, Sendai, 980-8574, Japan.Deparment of Anatomy & Physiology, Cell Physiology Laboratory, Kansas State University, 228 Coles Hall, Manhattan, KS 66506-5802, USA.Department of Anatomy & Physiology, Cellular Biophysics Laboratory, Kansas State University, 228 Coles Hall, Manhattan, KS, 66506-5802, USA. marcus@ksu.edu.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

27515813

Citation

Miyazaki, Hiromitsu, et al. "The Gastric H,K-ATPase in Stria Vascularis Contributes to pH Regulation of Cochlear Endolymph but Not to K Secretion." BMC Physiology, vol. 17, no. 1, 2016, p. 1.
Miyazaki H, Wangemann P, Marcus DC. The gastric H,K-ATPase in stria vascularis contributes to pH regulation of cochlear endolymph but not to K secretion. BMC Physiol. 2016;17(1):1.
Miyazaki, H., Wangemann, P., & Marcus, D. C. (2016). The gastric H,K-ATPase in stria vascularis contributes to pH regulation of cochlear endolymph but not to K secretion. BMC Physiology, 17(1), p. 1. doi:10.1186/s12899-016-0024-1.
Miyazaki H, Wangemann P, Marcus DC. The Gastric H,K-ATPase in Stria Vascularis Contributes to pH Regulation of Cochlear Endolymph but Not to K Secretion. BMC Physiol. 2016 Aug 11;17(1):1. PubMed PMID: 27515813.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The gastric H,K-ATPase in stria vascularis contributes to pH regulation of cochlear endolymph but not to K secretion. AU - Miyazaki,Hiromitsu, AU - Wangemann,Philine, AU - Marcus,Daniel C, Y1 - 2016/08/11/ PY - 2016/04/01/received PY - 2016/07/29/accepted PY - 2016/8/13/entrez PY - 2016/8/16/pubmed PY - 2017/1/14/medline KW - Acid–base balance KW - Endolymph KW - Hydrogen ion secretion KW - Inner ear KW - Ion-selective self-referencing electrode KW - Potassium secretion KW - Stria vascularis SP - 1 EP - 1 JF - BMC physiology JO - BMC Physiol. VL - 17 IS - 1 N2 - BACKGROUND: Disturbance of acid-base balance in the inner ear is known to be associated with hearing loss in a number of conditions including genetic mutations and pharmacologic interventions. Several previous physiologic and immunohistochemical observations lead to proposals of the involvement of acid-base transporters in stria vascularis. RESULTS: We directly measured acid flux in vitro from the apical side of isolated stria vascularis from adult C57Bl/6 mice with a novel constant-perfusion pH-selective self-referencing probe. Acid efflux that depended on metabolism and ion transport was observed from the apical side of stria vascularis. The acid flux was decreased to about 40 % of control by removal of the metabolic substrate (glucose-free) and by inhibition of the sodium pump (ouabain). The flux was also decreased a) by inhibition of Na,H-exchangers by amiloride, dimethylamiloride (DMA), S3226 and Hoe694, b) by inhibition of Na,2Cl,K-cotransporter (NKCC1) by bumetanide, and c) by the likely inhibition of HCO3/anion exchange by DIDS. By contrast, the acid flux was increased by inhibition of gastric H,K-ATPase (SCH28080) but was not affected by an inhibitor of vH-ATPase (bafilomycin).  K flux from stria vascularis was reduced less than 5 % by SCH28080. CONCLUSIONS: These observations suggest that stria vascularis may be an important site of control of cochlear acid-base balance and demonstrate a functional role of several acid-base transporters in stria vascularis, including basolateral H,K-ATPase and apical Na,H-exchange. Previous suggestions that H secretion is mediated by an apical vH-ATPase and that basolateral H,K-ATPase contributes importantly to K secretion in stria vascularis are not supported. These results advance our understanding of inner ear acid-base balance and provide a stronger basis to interpret the etiology of genetic and pharmacologic cochlear dysfunctions that are influenced by endolymphatic pH. SN - 1472-6793 UR - https://www.unboundmedicine.com/medline/citation/27515813/The_gastric_HK_ATPase_in_stria_vascularis_contributes_to_pH_regulation_of_cochlear_endolymph_but_not_to_K_secretion_ L2 - https://bmcphysiol.biomedcentral.com/articles/10.1186/s12899-016-0024-1 DB - PRIME DP - Unbound Medicine ER -