Investigation of presence and absence of nitric oxide synthase (NOS) in sphincter of oddi (SO) and gallbladder (GB) from rabbits

Background and Aims: Organic nitrates confer relief on SO spasm but they are of limited influence on the GB. We studied whether the greater efficacy of nitroglycerin (NG) to relax the SO relative to the GB was underlain by a difference in bioconversion of NG to nitric oxide (NO). We investigated the presence and absence of NOS in both organs. Methods: Relaxation of isolated SO and GB muscle rings were studied by isometric tension measurement. After a stable contraction (KCl; 30 and 140 mM), the rings were exposed to cumulative increases in NG (0.1 nM –1µM) concentrations. Furthermore, we measured the relaxing ef…