Differential Regulation of Contractility and Nitric Oxide Sensitivity in Gravid and Nongravid Myometrium during Late Pregnancy in a Marsupial¹

Abstract

Marsupials have two anatomically separate uteri; and in macropodids (kangaroos and wallabies), there is a single ovulation from alternate ovaries in each cycle. During late pregnancy, the two uteri are differentially regulated by local hormonal influences from the corpus luteum, the fetus, and placenta on one side and by the developing Graafian follicle on the other. In this study, we report striking differences in contractile behavior of nongravid and gravid myometrium from the tammar wallaby (Macropus eugenii) in late pregnancy and immediately post partum. Nongravid myometrium, from the uterus ipsilateral to a Graafian follicle, was spontaneously active but unresponsive to the oxytocic peptide mesotocin and the smooth muscle relaxant nitric oxide. Myometrium from the contralateral, gravid uterus, which contained a conceptus and was associated with an active corpus luteum, was not spontaneously active. Gravid myometrium became increasingly sensitive to mesotocin stimulation as pregnancy progressed, and nitric oxide induced marked relaxation at all stages examined, by a guanylyl-cyclase mediated pathway. These results provide further evidence that the two uteri of marsupials are under differential control, suggesting that local endocrine and paracrine influences, derived from the ovaries, the fetus, and placenta, can regulate concurrent but distinct physiological responses in the reproductive tracts of these mammals.

Impairments in metabolism of amino acids — precursors of gasotransmitters — in the premature birth

“…В настоящее время известны три газотрансмиттера: оксид азота (NO), монооксид углерода (CO) и сероводород (H 2 S). Первым по времени открытия является NO, свободнорадикальная природа которого определяет его окислительное действие на клеточные компоненты, а выраженные вазодилататорные эффекты объясняют широкий спектр биорегуляторного действия этой молекулы [1][2][3][4]. Второй газотрансмиттер CO также относится к вазодилататорам, регуляторам окислительно-восстановительных процессов, ангиогенеза, ингибиторам апоптоза [5,6].…”