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 eff ects of cholecystokinin (CCK) octapeptide (CCK-8) on pepsinogen releas e from freshly isolated and from cultured porcine chief cells. CCK-8 h ad no significant effect on freshly isolated porcine chief cells but s timulated 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. I n 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 antagon ist devazepide (10 nmol/l) prevented the stimulatory effect of 1 mu mo l/l CCK-8 on pepsinogen release of 60-hour cultured cells. The adenyla te cyclase activator forskolin (10 mu mol/l) potentiated the low conce ntration CCK-8 effect, shifting the peak stimulation to a CCK-8 concen tration of 10 pmol/l, and inhibited the high concentration CCK-8 effec t on 60-hour cultured cells. These results indicate a time-dependent r ecovery of the CCK response of porcine gastric chief cells in monolaye r culture and suggest that this model has an advantage over freshly is olated chief cells with regard to the pharmacological characterization of CCK effects.