1. Plasma noradrenaline concentrations and dopamine β-hydroxylase activity have been measured at various stages in the development of hypertension in the one-kidney Goldblatt rat (unilateral renal arterial constriction and contralateral nephrectomy).
2. Although plasma noradrenaline concentrations were significantly elevated from control values at 7, 14 and 28 days, plasma dopamine β-hydroxylase activity was not significantly different from control values except at 24 h.
3. These findings suggest that peripheral sympathetic activity is increased in the one-kidney Goldblatt model of experimental hypertension but that plasma dopamine β-hydroxylase activity is a poor index of this increase.
4. Both the rise in blood pressure and the rise in plasma noradrenaline concentrations were prevented by pretreatment with intracisternal 6-hydroxydopamine, suggesting that the increased sympathetic activity is at least in part centrally mediated.