Detection of guanylate cyclases A and B stimulated by natriuretic peptides in gastrointestinal tract of rat.
The ultracytochemical localization of membrane-bound guanylate cyclases A and B has been studied after stimulation with atrial natriuretic peptide, C-type natriuretic peptide and brain natriuretic peptide in the gastrointestinal tract of rat. The two isoforms are stimulated differently by the three peptides. The results showed that the atrial and C-type natriuretic peptides stimulated guanylate cyclase activity, whereas the brain peptide seemed not to activate enough of the enzyme to detect. The guanylate cyclase activity had a wider distribution in stomach and small intestine than in large intestine; nevertheless, the reaction product of guanylate cyclase A activity had a wider localization in the stomach, whereas the reaction product of guanylate cyclase B activity had a wider distribution in the small intestine. In the small and large intestine, we detected mostly similar localizations of guanylate cyclase activity irrespective of the peptide used; in the stomach the reaction products of guanylate cyclase A and B were detected in different cell types or in different sites of the same cell. In all the gastrointestinal tract, guanylate cyclase activity was detected mainly in three types of cells: exocrine and endocrine cells; undifferentiated and mature epithelial cells; and smooth muscle cells. These localizations of guanylate cyclase activity suggest its role in regulating glandular secretion, cellular proliferation and muscular activity.
Rambotti
M G
MG
Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Italy.
Giambanco
I
I
Spreca
A
A
D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology; D002462:Cell Membrane / Q000201:enzymology; D004064:Digestive System / Q000201:enzymology* / Q000648:ultrastructure; D004789:Enzyme Activation; D006162:Guanylate Cyclase / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism*; D008854:Microscopy, Electron; D020097:Natriuretic Peptide, Brain; D020098:Natriuretic Peptide, C-Type; D009419:Nerve Tissue Proteins / Q000494:pharmacology; D011506:Proteins / Q000494:pharmacology; D051381:Rats
D007527:Isoenzymes; D009419:Nerve Tissue Proteins; D011506:Proteins; D020097:Natriuretic Peptide, Brain; D020098:Natriuretic Peptide, C-Type; D009320:Atrial Natriuretic Factor; D006162:Guanylate Cyclase