Characteristics of deslanoside-induced modulation on jejunal contractility

AIM： To characterize the dual effects of deslanoside on the contractility of jejunal smooth muscle. METHODS： Eight pairs of different low and high con- tractile states of isolated jejunal smooth muscle frag- ment （JSMF） were established. Contractile amplitude of JSMF in different low and high contractile states was selected to determine the effects of deslanoside, and Western blotting analysis was performed to measure the effects of deslanoside on myosin phosphorylation of jejunal smooth muscle. RESULTS： Stimulatory effects on the contractility of JSMF were induced （45.3% ± 4.0% vs 87.0% ±7.8%, P 〈 0.01） by deslanoside in 8 low contractile states, and inhibitory effects were induced （180.6% ± 17.8% vs 109.9% ± 10.8%, P 〈 0.01） on the contractility of JSMF in 8 high contractile states. The effect of desla- noside on the phosphorylation of myosin light chain of JSMF in low （78.1% ± 4.1% vs 96.0% ± 8.1%, P 〈 0.01） and high contractile state （139.2% ± 8.5% vs 105.5 ± 7.34, P 〈 0.01） was also bidirectional. Bidirectional regulation （BR） was abolished in the presence of tetrodotoxin. Deslanoside did not affect jejunal con- tractility pretreated with the Ca2 channel blocker vera- pamil or in a Ca2-free assay condition. The stimulatory effect of deslanoside on JSMF in a low contractile state （low Ca2 induced） was abolished by atropine. The inhibitory effect of deslanoside on jejunal contractil- ity in a high contractile state （high Ca2 induced） was blocked by phentolamine, propranolol and L-NG-nitro- arginine, respectively. CONCLUSION： Deslanoside-induced BR is Ca2 dependent and is related to cholinergic and adrenergic systems when JSMF is in low or high contractile states,