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Ion transport mechanisms responsible for K+ secretion and the transepithelial voltage across marginal cells of stria vascularis in vitro.
Hear Res. 1995 Apr; 84(1-2):19-29.HR

Abstract

It has long been accepted that marginal cells of stria vascularis are involved in the generation of the endocochlear potential and the secretion of K+. The present study was designed to provide evidence for this hypothesis and for a cell model proposed to explain K+ secretion and the generation of the endocochlear potential. Stria vascularis from the cochlea of the gerbil was isolated and mounted into a micro-Ussing chamber such that the apical and basolateral membrane of marginal cells could be perfused independently. In this preparation, the transepithelial voltage (Vt) and resistance (Rt) were measured across marginal cells and the resulting equivalent short circuit current (Isc) was calculated (Isc = Vt/Rt). Further, K+ secretion (JK+,probe) was measured with a K(+)-selective vibrating probe in the vicinity of the apical membrane. In the absence of extrinsic chemical driving forces, when both sides of the marginal cell epithelium were bathed with a perilymph-like solution, Vt was 8 mV (apical side positive), Rt was 10 ohm-cm2 and Isc was 850 microA/cm2 (N = 27). JK+,probe was outwardly directed from the apical membrane and reversibly inhibited by basolateral bumetanide, a blocker of the Na+/Cl-/K+ cotransporter. On the basolateral but not apical side, oubain and bumetanide each caused a decline of Vt and an increase of Rt suggesting the presence of the Na,K-ATPase and the Na+/Cl-/K+ cotransporter in the basolateral membrane. The responses to [Cl-] steps demonstrated a significant Cl- conductance in the basolateral membrane and a small Cl- conductance in the paracellular pathway or the apical membrane. The responses to [Na+] steps demonstrated no significant Na+ conductance in the basolateral membrane and a small Na+ or nonselective cation conductance in the apical membrane or paracellular pathway. The responses to [K+] steps demonstrated a large K+ conductance in the apical membrane. Apical application of 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) and basolateral elevation of K+ caused an increase in Vt and a decrease in Rt consistent with stimulation of the apical K+ conductance. Similar observations have been made in vestibular dark cells, which suggest that strial marginal cells and vestibular dark cells are homologous and transport ions by the same pathways. Taken together, these observations are incompatible with a model for the generation of the endocochlear potential which ascribes the entire potential to the strial marginal cells [Offner et al. (1987) Hear. Res. 29, 117-124].(

ABSTRACT

TRUNCATED AT 400 WORDS)

Authors+Show Affiliations

Cell Physiology Laboratory, Boystown National Research Hospital, Omaha, NE 68131, USA.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

7642451

Citation

Wangemann, P, et al. "Ion Transport Mechanisms Responsible for K+ Secretion and the Transepithelial Voltage Across Marginal Cells of Stria Vascularis in Vitro." Hearing Research, vol. 84, no. 1-2, 1995, pp. 19-29.
Wangemann P, Liu J, Marcus DC. Ion transport mechanisms responsible for K+ secretion and the transepithelial voltage across marginal cells of stria vascularis in vitro. Hear Res. 1995;84(1-2):19-29.
Wangemann, P., Liu, J., & Marcus, D. C. (1995). Ion transport mechanisms responsible for K+ secretion and the transepithelial voltage across marginal cells of stria vascularis in vitro. Hearing Research, 84(1-2), 19-29.
Wangemann P, Liu J, Marcus DC. Ion Transport Mechanisms Responsible for K+ Secretion and the Transepithelial Voltage Across Marginal Cells of Stria Vascularis in Vitro. Hear Res. 1995;84(1-2):19-29. PubMed PMID: 7642451.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Ion transport mechanisms responsible for K+ secretion and the transepithelial voltage across marginal cells of stria vascularis in vitro. AU - Wangemann,P, AU - Liu,J, AU - Marcus,D C, PY - 1995/4/1/pubmed PY - 1995/4/1/medline PY - 1995/4/1/entrez SP - 19 EP - 29 JF - Hearing research JO - Hear. Res. VL - 84 IS - 1-2 N2 - It has long been accepted that marginal cells of stria vascularis are involved in the generation of the endocochlear potential and the secretion of K+. The present study was designed to provide evidence for this hypothesis and for a cell model proposed to explain K+ secretion and the generation of the endocochlear potential. Stria vascularis from the cochlea of the gerbil was isolated and mounted into a micro-Ussing chamber such that the apical and basolateral membrane of marginal cells could be perfused independently. In this preparation, the transepithelial voltage (Vt) and resistance (Rt) were measured across marginal cells and the resulting equivalent short circuit current (Isc) was calculated (Isc = Vt/Rt). Further, K+ secretion (JK+,probe) was measured with a K(+)-selective vibrating probe in the vicinity of the apical membrane. In the absence of extrinsic chemical driving forces, when both sides of the marginal cell epithelium were bathed with a perilymph-like solution, Vt was 8 mV (apical side positive), Rt was 10 ohm-cm2 and Isc was 850 microA/cm2 (N = 27). JK+,probe was outwardly directed from the apical membrane and reversibly inhibited by basolateral bumetanide, a blocker of the Na+/Cl-/K+ cotransporter. On the basolateral but not apical side, oubain and bumetanide each caused a decline of Vt and an increase of Rt suggesting the presence of the Na,K-ATPase and the Na+/Cl-/K+ cotransporter in the basolateral membrane. The responses to [Cl-] steps demonstrated a significant Cl- conductance in the basolateral membrane and a small Cl- conductance in the paracellular pathway or the apical membrane. The responses to [Na+] steps demonstrated no significant Na+ conductance in the basolateral membrane and a small Na+ or nonselective cation conductance in the apical membrane or paracellular pathway. The responses to [K+] steps demonstrated a large K+ conductance in the apical membrane. Apical application of 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) and basolateral elevation of K+ caused an increase in Vt and a decrease in Rt consistent with stimulation of the apical K+ conductance. Similar observations have been made in vestibular dark cells, which suggest that strial marginal cells and vestibular dark cells are homologous and transport ions by the same pathways. Taken together, these observations are incompatible with a model for the generation of the endocochlear potential which ascribes the entire potential to the strial marginal cells [Offner et al. (1987) Hear. Res. 29, 117-124].(ABSTRACT TRUNCATED AT 400 WORDS) SN - 0378-5955 UR - https://www.unboundmedicine.com/medline/citation/7642451/Ion_transport_mechanisms_responsible_for_K+_secretion_and_the_transepithelial_voltage_across_marginal_cells_of_stria_vascularis_in_vitro_ L2 - https://linkinghub.elsevier.com/retrieve/pii/0378-5955(95)00009-S DB - PRIME DP - Unbound Medicine ER -