Perturbations in blood Ca2+ do not affect the activity of rat stomach enterochromaffin-like cells

Background: Gastrin stimulates uptake of Ca2+ into bone and causes transient hypocalcemia, possibly by releasing a peptide hormone from enterochromaffin-like (ECL) cells, which are histamine- and peptide-hormone-producing cells in the acid-producing part of the stomach. However, if ECL cells secrete a calciotropic hormone, it is to be expected that their activity is affected by the serum Ca2+ concentration. Methods: Food-deprived male rats were infused with human (Leu)(15)-gastrin-17 and/or ethylenediaminetetraacetic acid and CaCl2. The blood Ca2+ level was monitored throughout the experiments (3 h), and the serum concentrations of gastrin, parathyroid hormone, and calcitonin were measured at death. The activity of the ECL cells was assessed by measuring the histidine decarboxylase (HDC) activity. Results. Gastrin produced the expected increase in HDC activity, but neither hyper- nor hypo-calcemia affected the HDC activity of either hypo- or hyper-gastrinemic rats. Conclusion: Perturbations in blood Ca2+ do not seem to affect ECL cells, which is at odds with the view that ECL cells harbor a calciotropic hormone.