Integration of biochemical functions of different cells of rat gastric mucosa for hydrochloric acid secretion

The regulation patterns of gastric acid secretion in rats were investigated. Pentagastrin and histamine stimulate gastric acid secretion, but the inhibitors of DNA-dependent synthesis of RNA and of proteins prevent only the pentagastrin action. It has been found that pentagastrin induces histidine d...

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Published in:Molecular and cellular biochemistry 1976-09, Vol.12 (3), p.181-191
Main Authors: Salganik, R I, Bersimbaev, R I, Argutinskaya, S V, Kiseleva, E V, Khristolyubova, N B, Deribas, V I
Format: Article
Language:English
Subjects:
Adenosine Triphosphatases - metabolism
Animals
Bicarbonates - pharmacology
Binding Sites
Carbonic Anhydrases - metabolism
Cyclic AMP - pharmacology
Enzyme Activation
Gastric Juice - metabolism
Gastric Mucosa - cytology
Gastric Mucosa - drug effects
Gastric Mucosa - metabolism
Histamine - metabolism
Histidine Decarboxylase - metabolism
Histocytochemistry
Isoenzymes - metabolism
Male
Pentagastrin - metabolism
Rats
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Summary:The regulation patterns of gastric acid secretion in rats were investigated. Pentagastrin and histamine stimulate gastric acid secretion, but the inhibitors of DNA-dependent synthesis of RNA and of proteins prevent only the pentagastrin action. It has been found that pentagastrin induces histidine decarboxylase in gastric mucosa, ensuring local accumulation of histamine. The latter activates adenylate cyclase and results in 3',5'-AMP accumulation in gastric tissues. The administration of pentagastrin, histamine or 3',5'-AMP enhances the activity of gastric carbonic anhydrase, the enzyme which takes part in HCl formation. The data suggest that these three compounds act sequentially (pentagastrin leads to histamine leads to3',5'-AMP) and the effect of the last one could be mediated through 3',5'-AMP dependent protein kinase. The experiments in vitro demonstrated that gastric carbonic anhydrase can be separated into two isoenzymes and thephosphorylation of one of them by the 3',5'-AMP dependent protein kinase sharply increases its activity. The findings raise the possibility that histamine and 3',5'-AMP, mediating gastrin action, form together with enzymes (histidine decarboxylase, adenylate cyclase, protein kinase, carbonic anhydrase) a caascade of amplifiers. Autoradiographic studies have shown that [3H]-pentagastrin is not bound by oxyntic cells but adheres preferentially to histamine-producing alpha-like endocrine cells and to the chief cells, while 3H-histamine adheres preferentially to oxyntic and to chief cells. Electron microscopy indicates that only pentagastrin (but not histamine) initiates in alpha-like endocrine cells ultrastructural changes characteristic for induction. Pentagastrin, histamine and 3',5'-AMP administration produces in oxyntic cells ultrastructural changes typical for the secretion processes. These results lead to assumption that pentagastrin (gastrin) induces histidine decarboxylase in alpha-like endocrine cells of gastric glands. Histamine which is secreted enhances adenylate cyclase activity in the neighbouring oxyntic cells where 3',5'-AMP dependent protein kinase activates carbonic anhydrase by means of phosphorylation. These different cells form, probably, a multicellular functional unit for gastric acid secretion.
ISSN:0300-8177
1573-4919
DOI:10.1007/BF01741716