Effects of selected vasoconstrictor agonists on isolated omental artery from premenopausal nonpregnant women and from normal and preeclamptic pregnant women

OBJECTIVE: Our purpose was to compare the responsiveness of omental resistance arteries from nonpregnant women and from normotensive and preeclamptic pregnant women to selected contractile agonists. STUDY DESIGN: Omental artery rings with intact endothelium from normotensive premenopausal nonpregnant women and from normal and preeclamptic pregnant women were mounted in Krebs-bicarbonate solution in organ baths for isometric tension recording. After the presence of endothelium was confirmed, cumulative concentrations of norepinephrine, serotonin, U46619, and endothelin-1 were added. Concentration-response curves were constructed and expressed as percentage of a reference 60 mmol/L potassium chloride contraction. Data analysis was by repeated-measures analysis of variance, Newman-Keuls test, and paired or unpaired Student t test, as appropriate. Statistical significance was by two-tailed p < 0.05. RESULTS: Endothelin-1 and U46619 increased tension similarly in all three groups. Norepinephrine increased tension in nonpregnant vessels to a greater extent than in either preeclamptic or pregnant vessels (nonpregnant 114.3 ± 5.42% vs pregnant 65.2% ± 10.5%, P < 0.05). Nonpregnant omental artery developed significantly greater tension than did pregnant tissue at three concentrations of norepinephrine (10^-5 mol/L, 3 x 10^-5 mol/L, 10^-4 mol/L), and preeclamptic vessels developed more tension than that from normal pregnant vessels at 3 x 10^-6 mol/L (p = 0.06) and 10^-3 mol/L (p < 0.05). There was a negligible change in tension with increasing concentrations of serotonin in the vessels from nonpregnant women; serotonin-induced contraction in the omental arteries from normotensive pregnant women and preeclamptic patients was <6% of the potassium chloride reference contraction, but this was significantly (p < 0.05) different from that of the nonpregnant women. CONCLUSIONS: Omental artery segments from nonpregnant, normotensive pregnant and preeclamptic women contract similarly to endothelin-1 and U46619 but exhibit variable responses to norepinephrine and serotonin.