| Natriuretic peptides (NPs) are a kind of polypeptide family with many bioactivities and they exert physiologic functions as hormone or neurotransmitter. Up to now, NPs include atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), C-type natriuretic peptide (CNP), dendroaspis natriuretic peptide (DNP), micrurus natriuretic peptide (MNP) and ventricular natriuretic peptide (VNP). They are distributed all over the body and exert natriuretic-diuretic, vasorelaxation and other functions designed to lower blood pressure and to control electrolytes homeostasis and so on. Since Vuolteenaho et al found immunoactivity for ANP in the stomach and small intestine of rats, the study of relationship between NPs and gastrointestinal function was precluded.Gastrointestinal functions were modulated by NPs through cyclic guanosine monophosphate (cGMP) signal transduction pathway. Cyclic nucleotides are widely distributed in many kinds of tissues or cells, and in among them cGMP is very important second messenger. cGMP play an important role of regulating many physiological functions in many tissues for example smooth muscles. Previous study demonstrated that there are two kind of cGMP generationsystems, one is nitric oxide (NO)-soluble guanylate cyclase (sGC)-cGMP systemand another is NPs-membrane-bound guanylate cyclase (mGC) or particulate guanylate cyclase (pGC). Both two kind of cGMP generation systems induced relaxation of different smooth muscles through cGMP signal transduction pathway. Our previous study indicated that natriuretic receptors (NPR) distributed all layers of gastric wall and its density was the largest in the antrum. The effect of CNP on gastric motility is summarized as below. CNP significantly inhibited spontaneous contraction of gastric circular and longitudinal smooth muscles in rat, guinea-pig and human, and there were some different between circular and longitudinal smooth muscles or among different animals; The inhibitory effect of... |
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