Adverse Interactions Between Pregnancy and a New Model of Systemic Hypertension Produced by Chronic Blockade of Endothelial Derived Relaxing Factor (EDRF) in the Rat

Abstract

Chronic blockade of the endogenous EDRF system has previously been reported to produce a model of hypertension and renal damage in rats. The present studies were conducted in conscious chronically catheterized rats to compare the renal hemodynamic and blood pressure responses to pregnancy in normal rats and during chronic EDRF blockade. In both moderate and severe hypertension produced by EDRF blockade, the normal late gestational fall in blood pressure is absent and blood pressure remains elevated at term. There was no midterm renal vasodilation or increase in GFR in the chronically hypertensive rats, also proteinuria developed close to term in hypertensive animals. The normal pregnant rat shows a marked plasma volume expansion as evidenced by significant falls in hematocrit close to term. This was suppressed in the hypertensive animals, particularly in the more severely hypertensive group. The chronically EDRF blocked hypertensive animals had a relatively poor maternal and fetal outcome compared to normal rats.

Key Words:

• Pregnancy
• rat
• hypertension
• EDRF blockade
• renal hemodynamics