Abstract
The effect of nilvadipine, a dihydropyridine derivative, on intracellular Ca2+ ([Ca2+] i) concentration was investigated in isolated vestibular guinea pig hair cells using calcium-sensitive dye Fura-2. A high potassium-induced ([Ca2+] i) increase was observed at nilvadipine concentrations of 100 nM and 10 nM, but was inhibited at 10, μM and 1, μM. Nilvadipine selectively inhibited the L-type Ca2+ channel compared to amlodipine, which non-selectively inhibited high-voltage activated Ca2+ channel subtypes. The results suggest that the inhibitory effect of nilvadipine on Ca2+ influx through the L-type Ca2+ channel in vestibular hair cells, combined with the increase of inner ear blood circulation, may prevent hair cell damage during ischemia.
