Recovery of cholecystokinin response of porcine gastric chief cells during monolayer culture

Cell isolation may impair secretory chief cell functions. To evaluate whether a monolayer culture results in a recovery, we compared the effects of cholecystokinin (CCK) octapeptide (CCK-8) on pepsinogen release from freshly isolated and from cultured porcine chief cells. CCK-8 had no significant effect on freshly isolated porcine chief cells but stimulated pepsinogen release from 36- and 60-hour cultured cells with EC(50) values of 180 and 130 nmol/l, respectively. Maximal stimulation, achieved at a concentration of 1 mu mol/l, amounted to 289 +/- 63 (p < 0.01) and 401 +/- 64% (p < 0.01) of the respective control value. In addition, the CCK-8 concentration-response curve for 60-hour,but not for 36-hour cultured chief cells displayed a second stimulatory peak at a CCK-8 concentration of 100 pmol/l (266 +/- 55% of control value, p < 0.05) with an EC(50) value of 16 pmol/l. The CCKA-receptor antagonist devazepide (10 nmol/l) prevented the stimulatory effect of 1 mu mol/l CCK-8 on pepsinogen release of 60-hour cultured cells. The adenylate cyclase activator forskolin (10 mu mol/l) potentiated the low concentration CCK-8 effect, shifting the peak stimulation to a CCK-8 concentration of 10 pmol/l, and inhibited the high concentration CCK-8 effect on 60-hour cultured cells. These results indicate a time-dependent recovery of the CCK response of porcine gastric chief cells in monolayer culture and suggest that this model has an advantage over freshly isolated chief cells with regard to the pharmacological characterization of CCK effects.