- The effect of misoprostol and cimetidine on gastric cell turnover was studied. Endoscopic biopsy specimens of fundic and antral mucosa were obtained from duodenal ulcer patients before and after 4 wk of therapy with cimetidine 1.2 g/day or misoprostol 800 μg/day. Biopsy specimens were incubated with [3H]thymidine. Glandular column length and number of labeled ceils were determined after autoradiography. There was no significant difference in column length of antral or fundic glands before or after therapy with cimetidine and misoprostol. The number of antral and fundic labeled cells was significantly decreased after misoprostol treatment (3.6 ± 0.3 and 4.6 ± 0.4, mean ± SE), as opposed to their respective number before therapy (6.9 ± 0.5 and 8.3 ± 0.8) (p < 0.01). On the other hand, after treatment with cimetidine, the number of antral and fundic labeled cells was significantly higher (11.8 ± 0.9 and 7.5 ± 1.0, respectively) as compared with their number before therapy (5.7 ± 0.5 and 5.6 ± 0.6, respectively). The decreased gastric cell turnover induced by misoprostol indicates that the trophic effect of prostanoids on gastric mucosa is not due to an increase in cellular kinetics. The increased gastric cell turnover induced by cimetidine may contribute to its therapeutic effect in peptic ulcer disease.