ABSTRACT
C-type natriuretic peptide (CNP) shows remarkable sequence homology to atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) within the 17-residue ring portion formed by a pair of cysteine residues and being the third member of the natriuretic peptide family. Sequence analysis reveals that there are at least two exons in the coding region for preproCNP. Mature forms of CNP in body are CNP22 and its N-termi-nally elongated form CNP53. As an agonist, CNP selectively bind to natriuretic peptide receptor B (NPR-B) which has a single member-spanning helical domain and exert its biological effects by activating its C-teminal guanylate cyclase to catalyse formation of cyclic guanosine monophosphate (cGMP). CNP can also bind to natriuretic peptidereceptor C (NPR-C) which has high binding affinities for all of the natriuretic peptides. The synthesis and release of CNP are regulated by many cy-tokines, and CNP is metabolized by two main pathways : internalization and degradation through the binding with NPR-C or hydrolysis by neutral endopeptidase. CNP and its receptor distribute widespreadly in various tissues including vessels, blood and central neural systems, and produce effects of vasodilation, antianxiely effect and regulations of cell proliferation and endocrine.
ABSTRACT
The present study was to investigate the analgesic effect and mechanism of meto-clopramide (MCP) on a rabbit visceral pain model. The results showed that MCP (8 mg? kg-1,iv) could produce a significant analgesic effect on visceral pain (P