Effects of sodium nitroprusside on movement of sphincter of Oddi in hypercholesterolemia rabbits

Abstract

Objective To study the effects of nitric oxide (NO) donor sodium nitroprusside (SNP) on the movement of sphincter of Oddi (SO) and different potassium channels in the hypercholesterolemia (CH) rabbits.Methods A total of 24 New Zealand rabbits were divided randomly into three groups:control group (n =8),experimental group of 4-aminopyridine (4-AP,n =8) and experimental group of tetraethylammonium (TEA,n =8).The rabbits in each group were fed on high-cholesterol diet for 8 week.By using the method of the isometric tension recording,the contractile response of SO rings to 4-AP and TEA,and the relaxant effect of SNP on SO rings in all groups were measured.Results The initial contraction of the average volatility was (0.144 ± 0.004) g,the average contraction frequency was (10.8 ± 1.1)/min.SO rings showed the contractile response to the cumulation concentrations of 4-AP,and the contraction frequency was significantly reduced in 4-AP group as compared with the control group (P＜0.05).With the final concentration of 16 mmol/L 4-AP,the relaxant effect of SNP on SO rings was significantly reduced as compared with control group (P ＜ 0.05).The accumulation concentrations of TEA could significantly shrink the SO muscle.The contraction was significantly increased,and the contraction frequency was significantly decreased in TEA group as compared with the control group (P ＜ 0.05).With the final concentration of 10 mmol/L TEA,relaxant effect of SNP on SO rings was also reduced as compared with the control group (P ＜ 0.05).Conclusion The NO donor SNP may play an important role in relaxation of the SO muscle through the KV and BKCa channels. Key words: Sphincter of Oddi dysfunction; Hypercholesterolemia; Muscle tension; Potassium channels; Nitric oxide