Functional parathyroid hormone receptors are present in an umbilical vein endothelial cell line

Acute parathyroid hormone exposure induces vascular smooth muscle relaxatio n. In contrast, continuous infusion of parathyroid hormone leads to vasocon striction and an elevation of blood pressure. Despite the known effects of parathyroid hormone on vascular smooth muscle, possible direct effects on t he vascular endothelium have not previously been investigated. Using a huma n umbilical vein endothelial cell line, we found that parathyroid hormone i ncreased both intracellular calcium and cellular cAMP content in these endo thelial cells. Furthermore, exposure of these cells to increasing concentra tions of parathyroid hormone stimulated both [H-3] thymidine incorporation and endothelin-1 secretion. Parathyroid hormone/parathyroid hormone-related peptide receptor mRNA could be detected at low levels in these cells. In s ummary, these data demonstrate that endothelium-derived cells contain funct ional parathyroid hormone receptors. The potential physiological role of th ese receptors remains to be determined.