Abstract
Adenylate cyclase (ACLase) and guanylate cyclase (GCLase) were studied in the gastric parietal cells of guinea pigs fed ad libitum and/or starved using the recently improved cytochemical method introduced by Fujimoto et al. (1981).
Generally, GCLase activity was intense in comparison with ACLase activity in the parietal cell. In both, acid-secreting parietal cell and nonsecreting parietal cell, the reaction products indicating both ACLase activity and GCLase activity were recognized on the cytoplasmic side of the basal and lateral membranes, and the lateral apical membrane showing the cell junction with a prominent tight junction. The activity on the basal membrane was stronger than that on the lateral membrane. There was no difference in the intensity of cyclases' activity between the acid-secreting parietal cell and the non-secreting parietal cell in general. GCLase activity was also observed on some tubulovesicles in the non-secreting parietal cell.
These findings suggest that the hormone-sensitive cyclase system is mainly localized on the basal membrane of the cell and that the tight junction of the parietal cell is regarded as the specialized junction.
