In order to determine whether Ala-Pro-Gly-Try-NH2 (APGW-amide) could affect mammalian excitable cells, we investigated the effect of APGW-amide in PC12 cells. APGW-amide caused a rapid [Ca2+]i elevation, which was completely prevented by elimination of extracellular Ca2+ with EGTA and inhibited by two L-type Ca2+ channel blockers. [Ca2+]i elevation was also blocked by a specific PKC inhibitor and prolonged pretreatment of cells with PMA. These results indicate that APGW-amide elevates [Ca2+]i in PC12 cells, possibly by Ca2+ influx via L-type Ca2+ channel activated by PKC.