Reflex sympathetic function in cortisol-induced hypertension in humans.

Nine healthy male subjects underwent measurement of reflex sympathetic function, pressor responsiveness and baroreflex sensitivity to phenylephrine (PE) and glyceryltrinitrate (GTN) before (C1) and following six days of treatment (E6) with cortisol (F), 200 mg/day. Seven subjects had washout studies (W) performed at least two weeks following the end of treatment. The BP responses to head tilt, isometric exercise and mental arithmetic were unaltered by F, however, there was a significant diminution of the diastolic BP response to cold pressor stimulus (delta DBP: 19 +/- 3 vs 25 +/- 5 vs 27 +/- 5 mmHg; E6 vs C1 vs W, p < 0.05 C1 vs E6 and W). Baroreflex sensitivity to PE was increased (28 +/- 3 vs 19 +/- 2 ms/mmHg, E6 vs C1, p = 0.03). These data demonstrate that increased BP during F treatment is not attributable to increased SNS activity, and suggest that SNS activity may be decreased by F.