Thyroid hormone affects both endothelial and vascular smooth muscle cells in rat arteries

Abstract

SAR, China, Peopleˈs Republic of The effect of thyroid hormone on vascular cells is controversial. The present study investigated in isolated arteries [with and without endothelium; suspended for isometric tension measurement] whether or not thyroid hormone causes relaxations in, or alleviates endothelial dysfunction in diabetic animals.Triiodothyronine, (T3) did not relax aortae of control rats with or without endothelium but caused endothelium‐independent decreases in tension in mesenteric arteries, suggesting an endothelium‐independent vasodilator effect of the hormone.In femoral arteries of rats with streptozotocin‐induced Type 1 diabetes, A23187 caused the release of endothelium‐derived contracting factors (EDCF). After four weeks of chronic treatment with T3, the contractions to A23187 of preparations with endothelium were unchanged, but those without endothelium were augmented, suggesting that the release of EDCF was reduced. Thus, thyroid hormone affects both endothelial and vascular smooth muscle cells in rat arteries.