Lack of nitrate tolerance in isosorbide dinitrate- and sodium nitroprusside-induced relaxation of rabbit internal anal sphincter

Figure 1 The relaxant effects of ISDN, SNP and papaverine, in isolated rabbit internal anal sphincter smooth muscle strips. Papaverine induced relaxation was accepted as 100%. Maximum relaxations of ISDN and SNP were expressed as percentage of relaxation induced by papaverine. Each curve represents the mean ± SE for 6 experiments.

Figure 2 The influence of in vitro isosorbide dinitrate (ISDN)-induced tolerance on relaxant effects of ISDN (A), relaxant effects of sodium nitroprusside (SNP) (B) and relaxant effects of electric field stimulation (C) compared with control values in isolated strips of internal anal sphincter smooth muscle. Each curve represents the mean ± SE for 6 experiments.