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  • Title: Dependence of endocochlear potential on basolateral Na+ and Cl- concentration: a study using vascular and perilymph perfusion.
    Author: Shindo M, Miyamoto M, Abe N, Shida S, Murakami Y, Imai Y.
    Journal: Jpn J Physiol; 1992; 42(4):617-30. PubMed ID: 1474679.
    Abstract:
    Inside-positive endocochlear potential (EP) and high potassium concentration in the endocochlear duct are generated by transepithelial K+ transport in marginal cells of the stria vascularis. In order to estimate the degree of involvement of Na+ and Cl- in K+ transport in marginal cells, EP in guinea pigs was measured under artificial vascular and perilymphatic perfusion in situ. Na+ depletion due to both vascular and perilymphatic perfusion decreased EP by -10.0 +/- 4.1 mV (delta EP = -86 +/- 5.2 mV, n = 5) from the control value of 78 +/- 4.3 mV (p < 0.01). Cl- depletion due to vascular and perilymphatic perfusion also decreased EP by -10.0 +/- 4.9 mV (delta EP = 8.5 +/- 4.8 mV, n = 6) from the control value of 77 +/- 5.1 mV (p < 0.01). However, under either vascular or perilymphatic perfusion, even lowering of Na+ or Cl- concentration in the perfusate decreased EP only slightly compared to the results under both vascular and perilymphatic perfusion. Furosemide, a blocker of Na+/K+/2Cl- symport, decreased EP under vascular perfusion. This dependency of EP on basolateral Na+ and Cl- concentration strongly suggests that K+ transport by the marginal cell is dependent on the basolateral Na+ and Cl- concentration, and that Na+/K+/2Cl- symport is raised as a possible mechanism for Na+ and Cl- dependency of EP.
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