The importance of the stomach in gastrin-induced hypocalcemia in the rat.

Hypocalcemia following gastrin administration occurs in thyroparathyroidectomized (TPTX) as well as thyroid intact rats. Hypophosphatemia does not accompany the hypocalcemia induced by gastrin. These data suggest that a mechanism other than release of calcitonin from the thyroid gland may be involved in this response in the rat. Neither adrenalectomy, nephrectomy, nor excision of the pancreas and small and large intestine altered the hypocalcemic response to gastrin. Gastrectomy, however, eliminated all hypocalcemia following administration of this polypeptide in both thyroid intact and TPTX rats. Removal of the antrum of the stomach did not influence the hypocalcemic response to gastrin. Resection of the proximal 75% of the stomach, however, inhibited the hypocalcemic response to gastrin as did total gastrectomy. Thus, in the rat, the proximal stomach appears to play an important role in mediating this response.