- Remember that the parietal cell has receptors for gastrin, histamine and ACh. Gastrin is released from the antral G-cells into the blood. This causes an increase in cytosolic Ca2+, which stimulates acid secretion from the H/K ATPase (the proton pump) on the canalicular surface.
- The H2 receptor antagonists are competitive antagonists of the H2 receptor. They are highly selective and do not affect H1 or H3 receptors.
- When given in usual doses, they inhibit 60-70% of 24 hour gastric secretion.
- Indications as follows:
- Peptic ulcer disease
- Adverse effects (with regards to cimetidine)
- Cimetidine inhibits binding of dihydrotestosterone to androgen receptors. This inhibits metabolism of estradiol and increases serum prolactin levels. It may cause gynecomastia or impotence in men, and galactorrhea in women.