Increased Capillary Permeability of the Stria Vascularis to HRP, Induced by Experimental Acute Hypotension in Rats

Abstract

Acute hypotension was produced in rats by using two experimental techniques: intravenous infusion of a ganglion-blocking agent (Arfonad), and venesection of a femoral vein. Horseradish peroxidase (HRP) was injected intravenously after each procedure, and subsequently observed in the inner ear by light and electron microscopy. In both experimental models, a large amount of tracer spread into the intercellular spaces, but it was halted by tight junctions bordering the stria vascularis. The endothelium exhibited a high distribution density of labelled vesicles, which suggested increased vesicular transport. There was no extravasation of HRP from capillaries in the spiral ligament in spite of the presence of some labelled pinocytotic vesicles. The present study was concerned with the discovery of enhanced capillary permeability of the stria vascularis under acute hypotension, as in the case of acute hypertension (Sakagami et al., 1984).

Response to a Letter to the Editor to ‘Folic acid improves inner ear vascularization in hyperhomocysteinemic mice’

“…This may support the notion that FA mitigates structural changes but has marginal effect on hearing. Gratton and Schulte (1995), Johnsson and Hawkins (1972), Sakagami et al (1984) and Ohlemiller et al (2008) reported alterations in microvasculature associated with atrophy of the stria vascularis in quitaged gerbils. Further, the cochlea has a rich vascular supply, which is embedded in double layer bed of epithelium, where the arterial supply breaks into minute capillaries (Gopinath et al, 2010).…”