Calcium channel blockade reduces noise-induced vascular permeability in cochlear stria vascularis.

Exposure to noise results in multiple perturbations of cochlear microcirculation, including increases in vascular permeability. There is evidence that these events are mediated, in part, by calcium channels. The current study examined the effects of calcium channel blockade on the diameter and permeability of cochlear vessels during noise exposure. Subjects were exposed to either noise alone or noise after verapamil pretreatment. Vessels of the cochlear stria vascularis were imaged using intravital microscopy. Animals exposed to noise showed decreases in diameter and increased permeability above baseline levels. Animals pretreated with the calcium channel blocker verapamil and exposed to noise demonstrated increases in vessel diameter and no changes in permeability. These data indicate that calcium channel blockade reduces noise-induced microvascular permeability. Treatment strategies designed to protect from increases in vascular permeability due to noise exposure may reduce temporary threshold shifts.