Endothelium is a Target Organ of Parathyroid Secretions in Genetic Hypertensive Rats

Abstract

We investigated the relationships between vascular endothelium and parathyroid function. Blood pressure (BP), circulating endothelins (ETs) and atrial natriuretic peptide (ANP), and BP responses to parathyroid hormone (PTH) and N^G-nitro-L-arginine methyl ester (L-NAME) were measured in parathyroidectomized (PTx), PTx and fed a Ca²⁺ enriched diet (PTx-HCa) and sham SHR. 22 weeks after surgery, BP was significantly decreased in PTx and PTx-HCa, plasma ETs levels were increased, whereas ANP levels were decreased. In anesthetized rats, BP increase induced by L-NAME was greater in PTx-HCa than in sham group, indicating increased endogenous nitric oxide release in hypoparathyroid rats. The hypotensive response to PTH remained unchanged. These data demonstrate that endothelium is activated in long-term hypoparathyroid SHR, reflecting an adaptative response to decreased BP.

Key words

ANP - Calcium - Endothelin - L-NAME - Nitric Oxide