Effects of arecoline on calcium channel currents and caffeine-induced calcium release in isolated single ventricular myocyte of guinea pig.

The effects of Arecoline (Are) on calcium mobilization were investigated. In isolated single ventricular myocyte of guinea pig, patch clamp whole cell recording techniques were used to record the current of L-type calcium channel and cytosolic Ca2+ level ([Ca2+]i) labeled with fluorescence probe Fluo-3/AM was measured under a laser scanning confocal microscope. Results revealed that Are (3-100 mumol/L) could inhibit L-type calcium current in a concentration-dependent manner and the value of IC50 was 33.73 mumol/L (n = 5). In the absence of extracellular calcium, the resting levels of [Ca2+]i was not affected by Are (n = 6, P > 0.05), but pretreatment with Are (30 mumol/L) could significantly inhibit the [Ca2+]i elevation induced by caffeine (10 mmol/L, n = 6, P < 0.01). It was concluded that Are could inhibit not only calcium influx through L-type calcium channel but also calcium release from sarcoplasmic reticulum.