The pressor hyperresponsiveness to phenylephrine unmasks sympathetic hypofunction in migraine.
The pressor responsiveness to phenylephrine, an almost pure agonist of peripheral alpha-1-adrenoceptors, was studied in 32 migraine patients in headache-free intervals. Eighteen healthy volunteers served as a control group. Fourteen patients and 14 controls also underwent the tilt test. The following observations were made: (1) the pressor response to phenylephrine was significantly greater and longer lasting in patients than in controls; (2) the reflex decrease of heart rate did not differ in the two groups; (3) a normal orthostatic increase of blood pressure and heart rate occurred in migraineurs with hyperresponsiveness to phenylephrine. These findings suggest a supersensitivity of vascular adrenoceptors which is compatible with a chronic adrenergic deficiency in migraineurs. Since patients did not show an orthostatic hypotension in attack-free periods, the compensatory character of receptoral supersensitivity and the possible mechanisms of cardiovascular dysautonomia, which may occur during migraineous attack, were discussed.
Boccuni
M
M
Institute of Internal Medicine and Clinical Pharmacology of Florence University, Italy.
Alessandri
M
M
Fusco
B M
BM
Cangi
F
F
D000328:Adult; D001342:Autonomic Nervous System Diseases / Q000175:diagnosis* / Q000503:physiopathology; D001794:Blood Pressure / Q000187:drug effects*; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D008881:Migraine Disorders / Q000175:diagnosis* / Q000503:physiopathology; D010656:Phenylephrine; D011187:Posture
D010656:Phenylephrine