Mineralocorticoid induced hypertension and noradrenaline spillover in man

This study examined haemodynamics and noradrenaline spillover in five normal men before and on day 7 of oral fludrocortisone treatment, 0.3 mg/day. Resting systolic (105 to 115 mm Hg, standard error of the difference +/- 2.0, p < 0.01) and diastolic (65 to 73 mm Hg, +/- 3.0, p < 0.05) blood pressure increased, as did cardiac output, from 5.0 to 5.7 L/min (+/- 0.1, p < 0.01). Calculated total peripheral resistance fell from 21.2 to 20.0 mm Hg/L/min (+/- 0.4, p < 0.05). Fludrocortisone produced a fall in plasma potassium, renin and aldosterone concentrations and haematocrit and a rise in body weight. Cold pressor responses were increased by fludrocortisone, from 7.5 to 20 mm Hg (+/- 3.0, p < 0.01), and forearm vascular resistance rose 12 arbitrary resistance units (R) before and 36 R units after treatment (+/- 5.0, p < 0.01). Total body spillover of noradrenaline was decreased from 9.48 to 7.36 ng/kg/min (+/- 0.86, p < 0.05). There were no changes in forearm noradrenaline spillover at rest or during cold pressor stimulation. It appears unlikely that the sympathetic nervous system plays a major role in the pathogenesis of mineralocorticoid hypertension in man.