ULTRACYTOCHEMICAL LOCALIZATION OF PARTICULATE GUANYLATE-CYCLASE AFTERSTIMULATION WITH NATRIURETIC PEPTIDES IN LAMB OLFACTORY MUCOSA

The ultracytochemical localization of particulate guanylate cyclase ha s been studied in lamb olfactory mucosa after activation with rat atri al natriuretic factor (rANF), porcine brain natriuretic peptide (pBNP) , porcine C-type natriuretic peptide (pCNP) or rat brain natriuretic p eptide (rBNP). Particulate guanylate cyclase is the receptor for these peptides and recently two subtypes of the cyclase have been identifie d. These isoforms are stimulated differently by ANF, BNP and CNP. Unde r our experimental conditions, rANF, pCNP and pBNP were strong activat ors of particulate guanylate cyclase in lamb olfactory mucosa, as demo nstrated by the presence of reaction product. Samples incubated in bas al conditions without rANF, pCNP or pBNP, or samples incubated in pres ence of rBNP did not reveal any cyclase activity. The rANF-stimulated cyclase activity was localized in the apical portion of olfactory epit helium. pCNP-stimulated guanylate cyclase was detected to the lamina p ropria in association with secretory cells of Bowman's glands and with cells in close relation with Bowman's glands (elongated cells and myo epithelial cells). The cyclase activity stimulated by pBNP was limited to cells of Bowman's glands. The present data indicate that ANF and C NP are recognized by different receptors and that BNP and CNP bind to the same receptor.