Venous Remodelling in the Pregnant RAT

Abstract

We tested the hypothesis that the capacitance veins remodel during pregnancy as indicated by significant alterations in their passive wall properties associated with changes in the extracellular protein matrix. Passive mechanics and the collagen and elastin concentrations of mesenteric veins isolated from virgin and late pregnant rats were determined. Veins were mounted in a pressurized system, the transmural pressure was increased from 2 to 10 mmHg. There was a significantly greater change in lumen diameter and axial length in the veins from the nonpregnant versus the pregnant rats. The stress-strain curve for the nonpregnant rats was shifted to the right of the pregnant animals with the slope of the tangential elastic moduli being greater in the veins from the nonpregnant rats, suggesting that these veins were less stiff than those from the pregnant animals. In contrast to the mechanical data, analysis of collagen and elastin concentrations demonstrated a decrease in the collagen and no change in the elastin in the veins from the pregnant rats.