Noradrenaline-induced vasoconstriction in the uterine vascular bed of pregnant rats chronically treated with L-NAME: role of prostanoids.
Vascular reactivity to vasoconstrictors has been observed in preeclamptic vessels. In this investigation, the possible role of endothelin-1 and endoperoxide/thromboxane receptor activation in the exaggerated response of the uterine vascular bed from rats with experimentally induced preeclampsia-like syndrome to noradrenaline was studied. The mean blood pressure in non-pregnant rats was 126.0 +/- 8.7 mm Hg (n = 5) while in pregnant rats, the mean blood pressure was 110.0 +/- 4.7 mm Hg (n = 5). Corresponding values in l-NAME-treated non-pregnant and pregnant rats were 167.5 +/- 6.9 mm Hg (n = 6) and 167.5 +/- 6.9 mm Hg (n = 6). These values were not significantly (P > 0.05) different from each other but were significantly (P < 0.05) different from corresponding values in control rats (not treated with l-NAME). Noradrenaline (10-10-10-6 mol) produced potent and reproducible vasoconstriction in isolated perfused rat uterine vascular bed from l-NAME-treated and untreated pregnant and non-pregnant rats. There was no significant difference in the potency of noradrenaline. However, there was an increase in the absolute maximum response to noradrenaline in uterine vascular bed from l-NAME-treated pregnant rats when compared with the other groups. Noradrenaline-induced vasoconstriction was not significantly affected by AT1-receptor antagonist, ZD 7155 or SB 209670, a potent ETA/ETB receptor antagonist. Vasoconstrictor responses to noradrenaline were however significantly reduced by indomethacin and SQ 29548 in l-NAME-treated pregnant rats. These observations would suggest that in pregnant rats treated with l-NAME, cyclooxygenase products play a significant role in noradrenaline-induced vasoconstriction of this preparation.
Yousif
Mariam H
MH
Department of Pharmacology, Kuwait University, Safat.
Chandrasekhar
Bindu
B
Kadavil
Elizabeth A
EA
Oriowo
Mabayoje A
MA
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005260:Female; D007213:Indomethacin / Q000494:pharmacology*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D009638:Norepinephrine / Q000494:pharmacology*; D011247:Pregnancy; D051381:Rats; D017208:Rats, Wistar; D014599:Uterus / Q000098:blood supply* / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects*; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
D004791:Enzyme Inhibitors; D014662:Vasoconstrictor Agents; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester; D009638:Norepinephrine; D007213:Indomethacin