OBJECTIVETo examine the effects of procaine and lidocaine on intracellular Ca(2+) release from sarcoplasmic reticulum ryanodine-sensitive Ca(2+) stores.

METHODSThe experiment was performed on hippocampal slices from 60-80 g male Mongolian gerbils. Levels of intracellular Ca(2+) concentration in the slices were measured by microfluorometry. The slices were perfused with 50 mmol/L KCl containing medium for 30 seconds. Then, the medium was switched to physiological medium. After 5 min of incubation, the slice was perfused with 20 mmol/L caffeine containing physiology medium for 2 min. Following incubation, the slice was superfused with physiological medium until the end of the experiment. The effects of procaine and lidocanin (100 micro mol/L) on caffeine-evoked Ca(2+) release were evaluated by adding them to the medium after high K(+) medium perfusion.

RESULTSCaffeine induced a marked increase in intracellular Ca(2+) concentration which was then decreased 12% upon the addition of procaine (P < 0.05); however, lidocaine, did not induce a similar inhibitory reaction.

CONCLUSIONProcaine inhibits ryanodine-receptor mediated Ca(2+) release from intracellular Ca(2+) stores, while lidocaine may inhibit Ca(2+) release through other mechanisms.