P46 The impact of hydrogen sulfide on ovalbumin-sensitized canine trachealis smooth muscle

Abstract

Background Hydrogen sulfide has been found to relax vascular smooth muscle, to function as a neuroprotectant molecule in the CNS in an extensive corpus of literature. However, very little has been reported regarding the effect of H2S on airway smooth muscle. Just as relaxation of vascular smooth muscle would be a benefit for hypertensive subjects, relaxation of airways smooth muscle would be helpful for asthmatic subjects. Methods Conventional force–velocity properties of the sensitized canine trachealis smooth muscle were measured with a muscle servo-motor system. Electrical field stimulation was provided to muscle strips in vitro. Results In the sensitized trachealis H2S reduced both the shortening and the velocity of shortening of the strip. The reduction in shortening was due to prolongation of the preceding relaxation. Analysis of the derivatives of shortening indicated that cross-bridge activity under H2S increased spontaneously during relaxation. Biochemical studies showed a spontaneous increase in both myosin light-chain phosphorylation and intracellular calcium as well as a decrease in myosin light-chain phosphatase activity. Further, both endogenous H2S synthesizing enzymes were reduced. Conclusion These results suggest a potential therapeutic pathway for asthma relief.