title: Uptake and incorporation of phosphate by frog gastric mucosa.
abstract: Labeled inorganic phosphate (32Pi) was used to follow uptake and incorporation of phosphate into high-energy intermediates of isolated bullfrog gastric mucosa. Dependence of uptake on levels of external Pi showed both saturable nonsaturable components. Measurements at 25 microM Pi, a level at which the saturable component was predominant, showed a strong dependence of Pi uptake on external Na+ and pH. Labeling of adenosine 5'-triphosphate (ATP) and creatine phosphate was rapid, followed by labeling of adenosine 5'-diphosphate, probably by way of adenylate kinase. Both alkaline nutrient pH and the uncoupling agent, dinitrophenol, reduced labeling of ATP with a concomitant inhibition of acid secretion. A feasible interpretation is that dinitrophenol acts by diminishing mitochondrial production of ATP, whereas alkaline pH reduces the utilization of ATP by the K+-ATPase considered to be responsible for acid production. The results thus agree with the hypothesis that ATP is the immediate substrate for secretion: only a part of the tissue ATP is directly available to the acid-producing mechanism, however.
mesh_terms: D000227:Adenine Nucleotides / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000502:physiology*; D000818:Animals; D005750:Gastric Juice / Q000378:metabolism*; D005753:Gastric Mucosa / Q000378:metabolism*; D006632:Histamine / Q000494:pharmacology; D008785:Metiamide / Q000494:pharmacology; D010710:Phosphates / Q000378:metabolism*; D011892:Rana catesbeiana; D012964:Sodium / Q000502:physiology; D013806:Theophylline / Q000494:pharmacology
chemical_list: D000227:Adenine Nucleotides; D010710:Phosphates; D008785:Metiamide; D006632:Histamine; D000255:Adenosine Triphosphate; D012964:Sodium; D013806:Theophylline