title: Effect of parathyroid hormone on bicarbonate secretion in the guinea-pig stomach and the amphibian isolated gastric mucosa.
abstract: 1. The effect of parathyroid hormone on gastric bicarbonate secretion was determined in the anaesthetized guinea pig. Subcutaneous injections of bovine parathyroid hormone (75 U.S.P units day-1 kg-1) for 7 days caused a significant increase in HCO3- output. There was also a rise in K+ output and a slight elevation of H+ secretion. A similar increase in HCO3- output occurred after acute intravenous injection of the hormones (75 U.S.P. units/kg). 2. Both chronic and acute administration of parathyroid hormone caused a significant increase in serum calcium concentration and it is likely that the changes in gastric ion outputs reflect raised calcium levels. Given alone intravenous calcium (1.5 mg/kg body wt.) stimulated gastric secretion of both HCO3- and H+. 3. To determine whether parathyroid hormone had a direct action on gastric ion transport experiments were performed in the amphibian isolate mucosa. Antrum transports HCO3- spontaneously while HCO3- transport in fundus was studied after inhibition of the greater H+ secretion by the histamine H2-receptor antagonist metiamide. Parathyroid hormone at a concentration of 0.2 United States Pharmacopea (U.S.P.) unit/ml in the nutrient-side bathing solution inhibited both antral and fundic HCO3- transport. A higher concentration (2.0 units/ml) had no effect on fundic H+ secretion. 4. The inhibitory effect in vitro was greater in the antrum and parathyroid hormone may almost abolish the active component of HCO3- transport in this tissue. It is likely that any similar inhibition of gastric HCO3- secretion by parathyroid hormone in vivo is masked by the stimulatory effects of released calcium.
mesh_terms: D000818:Animals; D001639:Bicarbonates / Q000378:metabolism*; D002118:Calcium / Q000097:blood / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005744:Gastric Acid / Q000378:metabolism; D005753:Gastric Mucosa / Q000378:metabolism*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D009337:Necturus; D010281:Parathyroid Hormone / Q000494:pharmacology*; D011896:Rana temporaria; D013997:Time Factors
chemical_list: D001639:Bicarbonates; D010281:Parathyroid Hormone; D002118:Calcium