Implication of parathyroid hormone for the development of hypertension in young spontaneously hypertensive rats

The purpose of this study is to elucidate the role of parathyroid hormone (PTH) in the development of hypertension in young spontaneously hypertensive rats (SHR). Parathyroidectomy (PTX) or sham surgery was performed on 6-week-old male SHR, and 3 weeks later human PTH (hPTH) or saline was infused subcutaneously over 2 weeks using a minipump. PTX significantly attenuated the development of hypertension and reduced serum vitamin-D concentrations. PTX also augmented the depressor response to acetylcholine before N-nitro-L-arginine (L-NNA), although it remained unchanged after L-NNA. The cardiovascular reactivity to exogenous noradrenaline and angiotensin II was not affected by PTX. The chronic administration of hPTH reversed these effects. We conclude that PTH plays an important role in the development of hypertension, through modulating the release of endothelium-derived relaxing factor, in young SHR.