Evidence for nitric oxide mediation of contractile activity in isolated strips of the human Fallopian tube

• Published in: Human reproduction (Oxford) 1997-02, Vol.12 (2), p.301-305
• Main Authors: Ekerhovd, E, Brännström, M, Alexandersson, M, Norström, A
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Enzyme Inhibitors - pharmacology; Fallopian Tubes - physiology; Female; Fundamental and applied biological sciences. Psychology; Humans; Mammalian female genital system; Morphology. Physiology; Muscle Contraction - drug effects; Muscle Contraction - physiology; NG-Nitroarginine Methyl Ester - pharmacology; Nitric Oxide - antagonists & inhibitors; Nitric Oxide - physiology; Vertebrates: reproduction
• ISSN: 0268-1161; 1460-2350
• DOI: 10.1093/humrep/12.2.301

Endogenously produced nitric oxide (NO) induces relaxation in smooth muscle in various organs. The purpose of this study was to investigate whether a NO-mediated relaxation system exists in the human Fallopian tube. To study contractility, the isthmic portion of the tube was obtained from 23 fertile women during operations due to benign non-tubal diseases. Tubal smooth muscle strips were mounted in tissue chambers containing HEPES buffer and connected to a Grass transducer for the isometric registration of contractile activity. By adding L-arginine (the substrate for NO synthesis) or N-nitro-L-arginine methyl ester (L-NAME; an inhibitor of NO synthesis) to the tissue chambers, changes in tubal contractility were monitored. The addition of L-NAME caused increased tubal contractility, while L-arginine, after an initial transient increase in tonus, caused relaxation of the strips. Using immunohistochemistry, NO synthase, the enzyme that catalyses the production of NO from L-arginine, was identified in tubal tissue cells. These results indicate that a NO-dependent relaxation system exists in the Fallopian tube and that NO may play a role as a mediator of tubal contractility.