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

Abstract

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.

Distribution of NADPH-diaphorase and Nitric Oxide Synthase (NOS) in Different Regions of Porcine Oviduct During the Estrous Cycle

“…Prostaglandin E 2 is a well-known factor that becomes increased at the postovulatory stage of the estrous cycle (Wijayagunawardane et al 1998) and is responsible for relaxation of the oviduct in the presence of progesterone (Hunter 1988). Because progesterone can be locally concentrated in blood, reaching the oviduct immediately after ovulation (Pharazyn et al 1991), it is possible that NO (apart from its own direct influence on oviduct; Ekerhovd et al 1997) activates cyclo-oxygenase enzymes to increase the production of PGE 2 . The increase of NADPH-d activity in myosalpinx exclusively at the postovulatory stage of the estrous cycle can be connected with relaxation of the oviduct for passage of embryos to the uterus after fertilization.…”

Novel type of interstitial cell (Cajal-like) in human fallopian tube

“…At the level of human fallopian tube, besides the well-known contractile effect of acetylcholine [111], the possible modulation of adrenergic neurotransmission by endogenous purines was reported [112], and purinergic receptors described [113]. Moreover, the involvement of NO/cGMP pathway in control of human fallopian tube contractility was established [114,115]. The strategical location of t-ICC, across the fallopian tube wall, shown in Fig.…”

Oviduct: roles in fertilization and early embryo development

“…This signaling pathway is upregulated during pregnancy and is mainly responsible for spontaneous oviduct muscle contraction, which provides a positive factor to the embryo movement toward the uterus (Ning et al 2014). Nitric oxide has been identified in the Fallopian tube; it mediates tubal muscle contraction, with possible roles in the regulation of sperm motility (Ekerhovd et al 1997, Kobayashi et al 2016. Dimethylarginine dimethylaminohydrolase 2 (DDAH2), an enzyme regulating nitric oxide synthesis, is also expressed in the oviduct in the presence of egg and embryo (Georgiou et al 2005).…”

“…It suggests that at least in these species, ciliary beating alone is capable of transporting the embryos from the oviduct to the uterus. In humans, oxytocin, P 4 , PGs and nitric oxide participate in the tubal muscle relaxation and contraction (Ekerhovd et al 1997, Jankovic et al 2001, Wanggren et al 2008. P 4 , through PGR-A and PGR-B relaxes muscle contraction in mice (Conneely et al 2003).…”