Antenatal/early postnatal hypothyroidism increases the contribution of Rho-kinase to contractile responses of mesenteric and skeletal muscle arteries in adult rats.

Background: Maternal thyroid deficiency can increase Rho-kinase procontractile influence in arteries of 2-week-old progeny. Here we hypothesized that augmented role of Rho-kinase persists in arteries from adult progeny of hypothyroid rats.

Methods: Dams were treated with 6-propyl-2-thiouracil (PTU) in drinking water (0.

Antenatal/early postnatal hypothyroidism alters arterial tone regulation in 2-week-old rats.

The mechanisms of vascular alterations resulting from early thyroid hormones deficiency are poorly understood. We tested the hypothesis that antenatal/early postnatal hypothyroidism would alter the activity of endothelial NO pathway and Rho-kinase pathway, which are specific for developing vasculature. Dams were treated with propylthiouracil (PTU, 7 ppm) in drinking water during gestation and 2 weeks after delivery, and their progeny had normal body weight but markedly reduced blood levels of thyroid hormones (ELISA).

NO-mediated anticontractile effect of the endothelium is abolished in coronary arteries of adult rats with antenatal/early postnatal hypothyroidism.

Introduction: Thyroid hormones are essential for proper development of many systems and organs, including circulatory system. Thyroid deficiency during pregnancy may affect the cardiovascular function in children early on and later in adulthood. However, long-term effects of early thyroid deficiency are poorly understood.

Endogenous oestrogens do not regulate endothelial nitric oxide production in early postnatal rats.

Previously we showed that endothelium of 1-2-weeks old rats exerts an anticontractile effect due to spontaneous NO production which correlates with a higher eNOS expression level compared to adult rats. Oestrogens are powerful regulators of eNOS expression and activity in arterial endothelium. This study tested the hypothesis that anticontractile influence of endothelium in young rats is regulated by endogenous oestrogens.