title: Effects of continuous infusion of endothelin-1 in pregnant sheep.
abstract: Plasma concentration of endothelin-1, a potent vasoconstrictor produced by the vascular endothelium, has been observed to be significantly increased in a number of pathophysiological states, including preeclampsia. In the present study we have evaluated the effects of elevated plasma endothelin-1 in pregnant sheep by continuous exogenous endothelin-1 administration. Nine pregnant ewes (110+/-5 days' gestation) were instrumented for measurements of maternal mean arterial pressure, renal blood flow, and uterine blood flow. After recovery, endothelin-1 was infused intravenously for 4 hours at a dose that was adjusted to raise mean arterial pressure by approximately 20 mm Hg by the end of the first hour (range 5 to 20 ng/kg per minute). Mean arterial pressure, renal blood flow, uterine blood flow, urinary protein excretion, hematocrit, and plasma endothelin-1 concentration were measured hourly, and renal and uterine vascular resistances were calculated. Endothelin-1 produced significant increases (% change from baseline at t=4 hours) in mean arterial pressure (45+/-8%), renal vascular resistance (353+/-66 %), and uterine vascular resistance (59+/-21%). Endothelin-1 also increased microvascular permeability both systemically and within the kidney, as suggested by marked increases in hematocrit (0.27+/-0.01 to 0.32+/-0.01) and urinary protein concentration (0.95+/-0.1 to 7.9+/-3.2 mg/mL per mg creatinine). There was a highly significant correlation (P<.0001) between plasma endothelin-1 and mean arterial pressure, renal vascular resistance, uterine vascular resistance, hematocrit, and urinary protein content in all sheep studied. In addition, plasma endothelin-1 corresponded well with the time course of the changes in cardiovascular parameters and urinary protein excretion observed. These results provide evidence to suggest that elevation of circulating endothelin-1 in pregnant sheep can produce cardiovascular and hemodynamic changes that in many ways resemble the human disease preeclampsia. This supports the hypothesis that endothelial cell damage and/or dysfunction that is associated with increased production of endothelin-1 could directly contribute to the progression of preeclampsia.
authors.affiliation: Department of Obstetrics and Gynecology, College of Medicine, University of Cincinnati, Ohio 45267-0526, USA. Suzanne.Greenberg@uc.edu
authors.forename: S G
authors.initials: SG
authors.lastname: Greenberg
authors.forename: R S
authors.initials: RS
authors.lastname: Baker
authors.forename: D
authors.initials: D
authors.lastname: Yang
authors.forename: K E
authors.initials: KE
authors.lastname: Clark
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D019332:Endothelin-1 / Q000008:administration & dosage / Q000097:blood* / Q000494:pharmacology*; D005260:Female; D006400:Hematocrit; D006439:Hemodynamics / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D007262:Infusions, Intravenous; D011225:Pre-Eclampsia / Q000503:physiopathology; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000187:drug effects / Q000502:physiology*; D011507:Proteinuria; D012039:Regional Blood Flow / Q000187:drug effects; D012079:Renal Circulation / Q000187:drug effects; D012756:Sheep; D013997:Time Factors; D014599:Uterus / Q000098:blood supply; D014655:Vascular Resistance / Q000187:drug effects
chemical_list: D019332:Endothelin-1