Reflex sympathetic function in cortisol-induced hypertension in humans

Area of Science:

• Cardiovascular physiology
• Endocrinology
• Autonomic nervous system function

Background:

• Cortisol, a primary glucocorticoid, influences cardiovascular function.
• The impact of short-term cortisol administration on sympathetic nervous system (SNS) activity and baroreflex sensitivity requires further elucidation.
• Previous research has not definitively established the relationship between exogenous cortisol and autonomic cardiovascular regulation.

Purpose of the Study:

• To investigate the effects of short-term cortisol administration on reflex sympathetic function, pressor responsiveness, and baroreflex sensitivity in healthy males.
• To determine if cortisol treatment alters blood pressure responses to various physiological stressors.
• To assess changes in baroreflex sensitivity following cortisol treatment and washout.

Main Methods:

• Nine healthy male subjects received 200 mg/day of cortisol for six days.
• Measurements included blood pressure (BP) responses to phenylephrine (PE), glyceryltrinitrate (GTN), head tilt, isometric exercise, mental arithmetic, and cold pressor stimulus.
• Baroreflex sensitivity was assessed using PE and GTN before (C1), during (E6), and after (W) cortisol treatment.

Main Results:

• Cortisol treatment significantly diminished the diastolic blood pressure response to the cold pressor stimulus (p < 0.05).
• Baroreflex sensitivity to phenylephrine was significantly increased after cortisol treatment (p = 0.03).
• Blood pressure responses to head tilt, isometric exercise, and mental arithmetic remained unaltered by cortisol.

Conclusions:

• Increased blood pressure during cortisol treatment is not due to enhanced sympathetic nervous system (SNS) activity.
• Short-term cortisol administration may lead to a decrease in SNS activity.
• Cortisol influences baroreflex sensitivity and autonomic cardiovascular regulation.