Elevation of Inducible Nitric Oxide Synthase Activity in Human Endometrium during Menstruation1

The conversion of [14C]arginine into [14C]citrulline as an indicator of nitric oxide synthesis was studied in uteri isolated from rats on different days of gestation, after labour and during dioestrus. Nitric oxide synthesis was present in uterine tissues isolated at each stage of gestation and also in tissues collected during dioestrus and after labour. Expression of neuronal nitric oxide synthase was not detectable at any of the stages studied. Endothelial nitric oxide synthase was present at all the stages studied, but there was a significant increase on day 13 of gestation and a decrease thereafter, with the lowest expression recorded on the day after labour. Inducible nitric oxide synthase expression in rat uteri increased substantially during pregnancy, with the highest expression on day 13 of gestation; expression decreased at term and after labour. The changes in expression of inducible nitric oxide synthase were coincident with the changes in nitric oxide synthase activity in uteri treated with aminoguanidine. Thus, these findings indicate that an increase in expression of inducible nitric oxide synthase in the uterus may be important for maintenance of uterine quiescence during pregnancy and its decrease near the time of labour could have an effect on the start of uterine contractility.

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Hemorrhagic Shock in Swine: Nitric Oxide and Potassium Sensitive Adenosine Triphosphate Channel Activation

Anesthesiology ◽

10.1097/00000542-200408000-00021 ◽

2004 ◽

Vol 101 (2) ◽

pp. 399-408 ◽

Cited By ~ 17

Author(s):

Jeffrey B. Musser ◽

Timothy B. Bentley ◽

Scott Griffith ◽

Pushpa Sharma ◽

John E. Karaian ◽

...

Keyword(s):

Nitric Oxide ◽

Mean Arterial Pressure ◽

Nitric Oxide Synthase ◽

Hemorrhagic Shock ◽

Inducible Nitric Oxide Synthase ◽

Katp Channel ◽

Channel Activation ◽

Oxide Synthase ◽

Nitric Oxide Synthase Activity ◽

Inducible Nitric Oxide

Background To determine the role of nitric oxide and adenosine triphosphate-sensitive potassium (KATP) vascular channels in vascular decompensation during controlled hemorrhagic shock in swine. Methods Thirty instrumented, anesthetized adolescent Yorkshire swine were subjected to controlled isobaric hemorrhage to a mean arterial pressure of 40 mmHg for 2 h (n = 6) or 4 h (n = 10) or 50 mmHg for 4 h (n = 8). An additional six animals were used as anesthetized instrumented time controls. During controlled hemorrhage, plasma and tissue samples were obtained every 30 to 60 min. Before euthanasia, tissue (carotid artery, lung, liver, and aorta) was obtained for analysis of nitrate concentrations and nitric oxide synthase activity. Isolated carotid artery ring reactivity to norepinephrine was also determined with and without glibenclamide. Results Animals hemorrhaged to 40 mmHg decompensated earlier than animals hemorrhaged to 50 mmHg. Plasma nitrate concentrations and nitric oxide synthase activity rose consistently throughout hemorrhage in both groups. However, they were substantially higher in the mean arterial pressure 40 group. Constitutive nitric oxide synthase activity was the major contributor to total nitric oxide synthase activity throughout the protocol with only the animals maintained at 40 mmHg for 4 h showing evidence of inducible nitric oxide synthase activity. Profound KATP channel activation and hyporeactivity of isolated vessel rings to norepinephrine was not observed until 4 h after the initiation of hemorrhagic shock. Only those animals with inducible nitric oxide synthase activity showed a decreased response to norepinephrine, and this hyporeactivity was reversed with the KATP channel inhibitor, glibenclamide. Conclusions The data indicate that profound KATP activation associated with increased nitric oxide concentrations and inducible nitric oxide synthase induction is a key factor in vascular smooth muscle hyporeactivity characteristic of the late decompensatory phase of hemorrhagic shock in swine.

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