Density of marginal cell basolateral membranes in basal, middle, and apical turns of the rat cochlea.
The Na-K-ATPase activity within stria vascularis tissues has been observed to decrease from basal to apical cochlear turns. This reduction in Na-K-ATPase activity in more apical regions of the cochlea may be accounted for, at least in part, by a lower density of Na-K-ATPase-containing basolateral membranes of the marginal cells. This study was performed to compare the surface density of marginal cell basolateral membranes in standardized basal, middle, and apical turns of the rat cochlea. Montages of transmission electron microscopic micrographs of standardized regions of the rat stria vascularis were morphometrically analyzed. Surface area of marginal cell basolateral membrane was determined per unit stria vascularis volume and per unit marginal cell volume. Results demonstrated that the surface density of marginal cell basolateral membrane per stria vascularis volume of the standardized basal region increased 20 percent compared to that of the standardized apical region (p < or = .1). Surface density of marginal cell basolateral membranes per marginal cell volume was similar in all three standardized turns. The observed longitudinal differences in surface density of marginal cell basolateral membranes per stria vascularis volume may account, in part, for the biochemical cochlear Na-K-ATPase activity gradient from base to apex.
ten Cate
W J
WJ
Department of Anatomy and Cell Biology, College of Medicine, University of Florida, Gainesville, USA.
Rarey
K E
KE
D000818:Animals; D002452:Cell Count; D002462:Cell Membrane / Q000378:metabolism*; D003051:Cochlea / Q000378:metabolism*; D046508:Culture Techniques; D051381:Rats / Q000502:physiology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D000254:Sodium-Potassium-Exchanging ATPase