Effects of diltiazem on [3H]-acetylcholine release in rat central nervous system

1. In the present study, we examined the effects of a Ca2+ channel blocker, diltiazem, on [3H]-acetylcholine (ACh) release in the rat CNS. 2. Diltiazem inhibited the electrically stimulated [3H]-ACh release in a dose-related fashion striatal slices of Sprague-Dawley (SD) rats. The basal release of [3H]-ACh was not significantly affected by diltiazem except at a high concentration. 3. The stimulation-evoked [3H]-ACh release was not different between spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats. 4. The inhibitory effect of diltiazem on the stimulation-evoked [3H]-ACh release was significantly greater in SHR than in WKY rats. 5. The results show that diltiazem inhibited the stimulation-evoked ACh release in the rat CNS. The pronounced effect of diltiazem in SHR suggests that the inhibition of central cholinergic activity might contribute, at least partially, to the hypotensive mechanisms of the Ca2+ channel blocker.