Mg. Rambotti et al., DETECTION OF GUANYLATE CYCLASE-A AND CYCLASE-B STIMULATED BY NATRIURETIC PEPTIDES IN GASTROINTESTINAL-TRACT OF RAT, Histochemical Journal, 29(2), 1997, pp. 117-126
The ultracytochemical localization of membrane-bound guanylate cyclase
s A and B has been studied after stimulation with atrial natriuretic p
eptide, C-type natriuretic peptide and brain natriuretic peptide in th
e gastrointestinal tract of rat. The two isoforms are stimulated diffe
rently by the three peptides. The results showed that the atrial and C
-type natriuretic peptides stimulated guanylate cyclase activity, wher
eas the brain peptide seemed not to activate enough of the enzyme to d
etect. The guanylate cyclase activity had a wider distribution in stom
ach and small intestine than in large intestine; nevertheless, the rea
ction product of guanylate cyclase A activity had a wider localization
in the stomach, whereas the reaction product of guanylate cyclase B a
ctivity had a wider distribution in the small intestine. In the small
and large intestine, we detected mostly similar localizations of guany
late cyclase activity irrespective of the peptide used; in the stomach
the reaction products of guanylate cyclase A and B were detected in d
ifferent cell types or in different sites of the same cell. In all the
gastrointestinal tract, guanylate cyclase activity was detected mainl
y in three types of cells: exocrine and endocrine cells; undifferentia
ted and mature epithelial cells; and smooth muscle cells, These locali
zations of guanylate cyclase activity suggest its role in regulating g
landular secretion, cellular proliferation and muscular activity.