Abstract:

Abstract:Objective
To examine the effects  of C-type natriuretic peptide (CNP) on the atrial dynamics and cylic nucleotides level in the atrial myocytes in rabbits and explore its mechanism of action. Methods  Atria were obtained from New Zealand white rabbits, and the experiments were performed using a  perfused beating atrial model. Briefly, the heart was removed from rabbit which had been anesthetized and the left atria was  dissected free, and then it was fixed in perfused beating atrial model. The effects of CNP (10, 30, or 300 nmol•L^-1) on atrial pulse pressure and atrial stroke volume were analyzed, and cAMP efflux and cGMP levels which were dealed with  30 nmol•L^-1 CNP were measured by radioimmnoassay . Results ①CNP (10, 30,and 300 nmol•L^-1) significantly decreased the atrial pulse pressure and atrial stroke volume in perfused beating atria compared with control group（P<0.05 or P<0.01）;these effects showed dose-dependent manner, and the maximum inhibitory rates in  300 nmol•L^-1  CNP group were 74.8% and 76.9%, respectively. ② 30 nmol•L^-1 CNP  significantly decreased the atrial pulse pressure and atrial stroke volume in perfused beating atria compared with control group（P<0.01）, and the cGMP level in the atrial myocytes was significantly increased, about 10.2 times,compared with control group(P<0.01), but the cAMP level didn’t  change (P>0.05).Conclusion CNP can inhibit the atrial dynamics,its mechanism may be related to the increasing of cGMP level through CNP-GC-cGMP signal pathway in rabbit atria. 

Key words: C-type natriuretic peptide, atrial function, cyclic nucleotide