Studies On The Relaxing Effect And Mechanism Of CY On Smooth Muscle

3, 4-dihydro-2-(4-morpholinylmethy)-l(2H)-naphthalenone (CY) was first synthesized by Welch, Willard M et al. in 1977 and its low analgesic activity was reported. There is no further study about CY. Here we first reported the relaxing effect of CY on smooth muscle. To investigate the effect and mechanism of CY on smooth muscle, experiments were carried out on isolated smooth muscle from rabbits and rice. CY was added at single dose to observe its effect on the spontaneous activity of small intestine from rabbits. Moreover, the effects of CY on smooth muscle preparations contracted with stimulants were studied on trachea, gallbladder, small intestine, colon and bladder. The study of the mechanism of CY was carried out on small intestine preparations of rabbits. In this paper the anti-diarrheal effect of CY was also investigated. The results suggested that CY in the concentration of 0.1 to 1 mM could dose-dependently decrease the amplitude and tension of spontaneous motility of rabbit small intestine but had no significant effect on the frequency. At the concentration of 0.01 to 3mM, CY could relax the contractions induced by Ach, high K⁺ solution and BaCl₂ on trachea, gallbladder, small intestine and colon of rabbits. On rabbit isolated bladder, the contractions induced by Ach and high K⁺ solution could also be relaxed by CY. Furthermore, the mechanism of CY had no relation to a, 6 receptors, PG, cGMP and K⁺ channel. To assess whether the spasmolytic activity of CY was through calcium channel blockade, the rabbit small intestine was used to obtain the CaCl₂ cumulative dose-response curves. CY caused a dose-dependent rightward shift in the Ca²⁺ dose-response curve, similar to that produced by verapamil, a well-known calcium antagonist. CY may produce its spasmolytic effect through voltage-dependent calcium channel. The antidiarrheal effects of CY were studied in mice. CY at the dose of 6.93 to 27.72mg/kg inhibited the diarrhea induced by castor oil, MgSO₄ and liquid paraffin in mice when administrated orally. In addition, the small intestinal transit in mice was delayed by CY. The latency of excreting black feces prolonged and this suggested that the movement of large bowel was inhibited by CY, too. Overall, the effects of CY on smooth muscle preparations in this study suggest that this...