P2y purinergic receptors coupled to phosphoinositide hydrolysis in tissues of the cochlear lateral wall.

The tissues of the lateral wall of the cochlea, spiral ligament and stria vascularis, maintain homeostasis of the inner ear through the production of endolymph and regulation of cochlear blood flow. We examined the effects of purinergic agonists on the release of inositol phosphates (InsPs) in intact isolated lateral wall tissues of the Fischer-344 rat. After preincubation with myo[3H]inositol, stimulation with the P2 purinergic agonist ATP-gamma-S resulted in a concentration-dependent increase in the formation of [3H]InsPs. The P2 purinergic agonist alpha,beta-methylene ATP (AMP-CPP) was a weaker stimulant, and the P1 purinergic agonist adenosine was ineffective. These results are consistent with the presence of P2y receptors and a purinergically controlled InsP3 second messenger system in the cochlear lateral wall.