Caffeine-induced Ca2+ release inhibits GABAA responsiveness in rat identified native primary afferents.

It has been shown previously that an increase in cytoplasmic Ca2+ concentration depresses the GABA-A response. However, little attention has been paid to the Ca2+ source involved. In the present study, we show that the Ca2+ increase triggered by caffeine-induced Ca2+ release from the intracellular pool inhibits the GABA-A response, whereas Ca2+ influx through voltage-activated Ca2+ channels has no effect on this response.