Parathyroidectomy increases peripheral vascular responsiveness to exogenous noradrenaline in the uraemic rat

The effect of surgical parathyroidectomy and/or cyclo-oxygenase inhibition on noradrenaline-induced blood pressure (BP) responses were investigated in a rat model of chronic uraemia. The blood pressure responses to noradrenaline were significantly lower in uraemic rats when compared with the responses of non-uraemic animals. Blood pressure responses of previously parathyroidectomized uraemic rats were significantly greater than sham-operated uraemic rats, as were the responses of uraemic rats pretreated with the cyclo-oxygenase inhibitor, indomethacin. Pretreatment of uraemic rats with both indomethacin and parathyroidectomy improved blood pressure responses to a degree equal to either manoeuvre alone, but did not exhibit an additive effect. These data suggest a role for parathyroid hormone and prostaglandins in the pathogenesis of the diminished noradrenaline responsiveness in uraemia, and suggest a common mechanism.