PCR and antisense oligodeoxy-neucleotide (ODN) blocking were used to identify a calcium (Ca) channel in rabbit proximal tubule (PT) cells. The subcloned Ca channel is identical to the rabbit cardiac Ca channel (alpha (1)) except a 33 base deletion at the fourth S3-S4 linker in PT cells. Anti-sense ODN treatment (18 h) inhibited 73 and 44% of Ca influxes induced by hypoosmotic stress (220 Osm) and by 1-oleoyl-2-acetyl-sn-glycerol (5 muM), respectively. The results indicate that the subcloned channel is a spliced variant of the cardiac Ca channel and that it plays a critical role in regulation of Ca signaling in these cells.