[Changes of [Ca2+]i in colorectal cancer cells induced by some chemicals]

Changes of [Ca2+]i in CCL229 cells induced by retionoic acid (RA), 1,25(OH)2VD3 and PMA were measured by spectrofluorometry. The effects of endoplasmic reticulum (ER)-specific Ca(2+)-ATPase inhibitor thapsigargin (TG) and IP3 receptor inhibitor heparin on RA-induced changes of [Ca2+]i were observed and the relationship between RA-induced changes of [Ca2+]i and ER was also investigated. The results showed that [Ca2+]i increased markedly in several seconds after treated by RA and 1,25(OH)2VD3. When cells were pretreated with EGTA and verapamil (Ca2+ entry blocker drug), TG could not inhibit RA-stimulated Ca2+ release from intracellular calcium pools and TG could increase [Ca2+]i after pretreated by RA. In addition, heparin could not completely inhibit RA-induced [Ca2+]i increase. The results suggest that RA might stimulate IP3-sensitive pool or IP3-insensitive pool on ER to increase [Ca2+]i, or there might be RA-sensitive calcium pools except ER in cells.