Role of nitric oxide on oxytocin-evoked contractions and prostaglandin synthesis in isolated pregnant rat uterus

Nitric oxide (NO) relaxes uterine smooth muscle and is produced by the pregnant uterus. Our previous studies revealed an increase in rat uterine NO synthase (NOS) activity in pregnancy and a decline at term. In the present study, we have examined the distribution of NOS isoform expression to determine whether their regulation is consistent with a role in the inhibition of uterine contractions before term. At day 17-18 of pregnancy, NOS immunohistochemistry revealed expression of two isoforms: endothelial constitutive form of NOS (ecNOS) in vascular endothelium and inducible form of NOS (iNOS) in myometrial and vascular smooth muscle and in decidual epithelium. Immunoblotting revealed that expression of iNOS declined nearly fivefold, whereas ecNOS declined twofold in laboring rats at term. We conclude that iNOS is expressed in myometrium of pregnant rat uterus but not the virgin rat and that iNOS expression declines at term when labor is present. The pattern of changes in myometrial iNOS expression with advancing gestation suggests that NO could act in an autocrine and/or paracrine manner to inhibit uterine contractions before term.

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Role of nitric oxide on the central hemodynamic response to acute volume expansion in the pregnant rat

American Journal of Obstetrics and Gynecology ◽

10.1016/s0002-9378(98)70499-5 ◽

1998 ◽

Vol 178 (4) ◽

pp. 823-829 ◽

Cited By ~ 3

Author(s):

Gabriel Fiol ◽

Francisco Machado ◽

Isabel Hernandez ◽

Andrés C. Inglés ◽

Lorenzo Abad ◽

...

Keyword(s):

Nitric Oxide ◽

Volume Expansion ◽

Hemodynamic Response ◽

Pregnant Rat ◽

Central Hemodynamic

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The effect of epidermal growth factor on prostaglandin synthesis of oestrogenized rat uterus is mediated by nitric oxide

Prostaglandins Leukotrienes and Essential Fatty Acids ◽

10.1054/plef.1999.0110 ◽

1999 ◽

Vol 61 (6) ◽

pp. 353-358 ◽

Cited By ~ 8

Author(s):

M.L. Ribeiro ◽

S. Perez Martinez ◽

M. Farina ◽

D. Ogando ◽

M. Gimeno ◽

...

Keyword(s):

Nitric Oxide ◽

Growth Factor ◽

Epidermal Growth Factor ◽

Prostaglandin Synthesis ◽

Rat Uterus ◽

Epidermal Growth

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IL1alpha augments prostaglandin synthesis in pregnant rat uteri by a nitric oxide mediated mechanism

Prostaglandins Leukotrienes and Essential Fatty Acids ◽

10.1054/plef.2000.0150 ◽

2000 ◽

Vol 62 (4) ◽

pp. 243-247 ◽

Cited By ~ 7

Author(s):

M. Farina ◽

M.L. Ribeiro ◽

D. Ogando ◽

M. Gimeno ◽

A.M. Franchi

Keyword(s):

Nitric Oxide ◽

Prostaglandin Synthesis ◽

Pregnant Rat

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Role of nitric oxide and prostaglandins in the regulation of diaphragmatic arteriolar tone in the rat

Journal of Applied Physiology ◽

10.1152/jappl.1994.77.2.590 ◽

1994 ◽

Vol 77 (2) ◽

pp. 590-596 ◽

Cited By ~ 23

Author(s):

J. Boczkowski ◽

E. Vicaut ◽

G. Danialou ◽

M. Aubier

Keyword(s):

Nitric Oxide ◽

Prostaglandin Synthesis ◽

Relative Importance ◽

Mechanically Ventilated ◽

Arteriolar Tone ◽

Dose Dependent Increase ◽

Dose Dependent ◽

Arteriolar Diameter ◽

Specific Inhibitors

We evaluated by intravital microscopy in rats the relative importance of nitric oxide (NO) and prostaglandins in 1) the maintenance of basal diaphragmatic arteriolar tone and 2) the response of diaphragmatic arterioles to the endothelium-dependent vasodilator acetylcholine (ACh). One hundred two mechanically ventilated rats were studied. Separate applications of N omega-nitro-L-arginine (L-NNA) and mefenamic acid (MA), which are specific inhibitors of NO and prostaglandin synthesis, respectively, elicited a significant reduction in basal diaphragmatic arteriolar diameter. A dramatic potentiation of the effect of each inhibitor was observed when both agents were applied simultaneously. ACh application induced a significant and dose-dependent increase in arteriolar diameter that was not significantly modified by the separate application of L-NNA or MA. Conversely, the simultaneous administration of L-NNA and MA almost completely prevented ACh-induced arteriolar dilatation. Dilatation in response to sodium nitroprusside was not significantly modified in the presence of both inhibitors. These results suggest that NO and prostaglandins act in concert to regulate basal diaphragmatic arteriolar tone and to mediate diaphragmatic arteriolar response to ACh.

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