title: Effect of minoxidil on sympathetic nervous activity in clonidine-treated hypertensive patients.
abstract: The effects of clonidine and minoxidil on sympathetic nervous activity has been studied in 10 patients with accelerated or resistant hypertension. Clonidine 150 to 900 micrograms/day caused a significant decrease in blood pressure of 18.6 mm Hg, of heart rate 16.4 beats/min, of plasma renin activity 1.13ng/ml h, and of urinary noradrenaline excretion 11.55 micrograms/day, and a significant lengthening of the pre-injection period of 12.4 ms. Minoxidil 5 to 22.5 micrograms/day caused a further significant decrease in blood pressure of 24.2 mm Hg, and significant increases in heart rate 8.2 beats/min, plasma renin activity 1.68 ng/ml h and of urinary noradrenaline excretion 5.0 micrograms/day, and a significant shortening of the pre-ejection period of 20.6 ms. Neither clonidine nor minoxidil altered plasma dopamine beta-hydroxylase activity or the cardiovascular responses to treadmill exercise. It is concluded that clonidine is a useful alternative agent to block a minoxidil-induced increase in sympathetic nervous activity.
mesh_terms: D000328:Adult; D002986:Clinical Trials as Topic; D003000:Clonidine / Q000008:administration & dosage*; D004359:Drug Therapy, Combination; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000201:enzymology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D008914:Minoxidil / Q000008:administration & dosage*; D011743:Pyrimidines / Q000008:administration & dosage*; D012083:Renin / Q000097:blood; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000503:physiopathology*
chemical_list: D011743:Pyrimidines; D008914:Minoxidil; D012083:Renin; D003000:Clonidine