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 re sistance arteries from nonpregnant women and from normotensive and pre eclamptic pregnant women to selected contractile agonists. STUDY DESIG N: Omental artery rings with intact endothelium from normotensive prem enopausal nonpregnant women and from normal and preeclamptic pregnant women were mounted in Krebs-bicarbonate solution in organ baths for is ometric tension recording. After the presence of endothelium was confi rmed, cumulative concentrations of norepinephrine, serotonin, U46619, and endothelin-1 were added. Concentration-response curves were constr ucted and expressed as percentage of a reference 60 mmol/L potassium c hloride contraction. Data analysis was by repeated-measures analysis o f variance, Newman-Keuls test, and paired or unpaired Student t test, as appropriate. Statistical significance was by two-tailed p < 0.05. R ESULTS: Endothelin-1 and U46619 increased tension similarly in all thr ee groups. Norepinephrine increased tension in nonpregnant vessels to a greater extent than in either preeclamptic or pregnant vessels (nonp regnant 114.3 +/- 5.42% vs pregnant 65.2% +/- 10.5%, p < 0.05). Nonpre gnant 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 (rho = 0.06) and 10(-5) mol/L (rho < 0.05). There was a negligible change in tension with increasing concentrations of serotonin in the v essels from nonpregnant women; serotonin-induced contraction in the om ental arteries from normotensive pregnant women and preeclamptic patie nts was <6% of the potassium chloride reference contraction, but this was significantly (rho < 0.05) different from that of the nonpregnant women. CONCLUSIONS: Omental artery segments from nonpregnant, normoten sive pregnant and preeclamptic women contract similarly to endothelin- 1 and U46619 but exhibit variable responses to norepinephrine and sero tonin.