[Effect of endogenous carbon monoxide on the smooth muscle function of dog penile corpus cavernosum in vitro].

Objective: To study the effect of endogenous carbon monoxide (CO) on the smooth muscle function of the dog penile corpus cavernosum in vitro.
Methods: Tissue bioassay was used to measure the corpus cavernosum muscle contraction and relaxation. The production of CO was induced in the corpus cavernosum smooth muscle, and the effect of CO on the penile corpus cavernosum smooth muscle pre-contracted by phenylephrine (PE) was determined.
Results: Chlorinous hemoglobin could relax the smooth muscle stripes pre-contracted by 10 micromol/L PE. A dose-dependent relaxation was observed. The relaxation responses by 10 -100 micromol/L chlorinous hemoglobin were significant compared with the control group (P < 0. 01). The pretreatment of the muscle stripes with ZnPP-IX or methylthioninium significantly reduced the relaxing effect of chlorinous hemoglobin (P < 0.01).
Conclusion: The relaxing effect of endogenous CO on the smooth muscle of the penile corpus cavernosum depends on the concentration of endogenous CO. The underlying mechanism may involve the pathway from CO to cGMP production.