Calcium modulates the synthesis of prostaglandin E2 in isolated colonic mucosal cells

Background/Aims: The effect of calcium on colonic prostaglandin E 2 synthesis was investigated in 26 healthy volunteers. Material and Methods: Biopsy specimens were obtained by colonoscopy and the mucosal cells were separated biochemically. The cells were incubated in EDTA or CaCl2 containing media for 15 and 30 minutes. Results: The PGE 2 synthesis was significantly (p< 0.001) diminished in the calcium free suspension (EDTA) compared to the CaCl 2 containing suspension. To increase intracellular Ca 2+ concentration, calcium ionophore A 23187 was added for the last 15 minutes. It significantly stimulated the prostaglandin production. In addition, the calcium channel blocker verapamil did not alter the PGE 2 synthesis, whereas trifluoperazine, a calmodulin inhibitor, markedly decreased the production rate. Conclusion: Calcium is an important stimulus of prostaglandin synthesis and inhibition of calmodulin by trifluoperazine decreases the arachidonic metabolism. In these regards, colonic tissue shares features with other tissues. However, in contrast to smooth or cardiac muscle, intracellular calcium concentration in colonic mucosa is not affected by verapamil, indicating that colonic calcium channels have a different affinity to this drug.