Effects of physiological and pharmacological variation of sympathetic nervous system activity on plasma non-esterified fatty acid concentrations in man.
1. The consequence of the sympatholytic effect of clonidine (alpha 2-adrenoceptor agonist) was compared with the effect of a physiological inhibition of sympathetic nervous system activity (change from upright to supine position) on plasma catecholamine and non-esterified fatty acid (NEFA) concentrations in overnight fasting healthy men. 2. Clonidine (150 micrograms orally) administered in upright position induced a significant reduction of plasma noradrenaline and NEFA concentrations. A change from upright to supine position which provoked a more marked decrease in plasma noradrenaline concentrations induced a weak increase in plasma NEFA concentrations. 3. The modification of plasma NEFA and catecholamine concentrations brought about by standing up was studied after placebo or yohimbine (alpha 2-adrenoceptor antagonist) administration. With placebo, standing up promotes a 100% increase in plasma noradrenaline concentrations (measured 5 and 15 min after rising) and a weak transient decrease in plasma NEFA concentrations (5 min after rising). In the supine position, yohimbine increased plasma noradrenaline and NEFA concentrations by about 100% and 55% respectively. Standing after yohimbine administration promoted large increases in plasma noradrenaline and NEFA concentrations. 4. These results indicate that a reduction of sympathetic nervous activity is not associated with a decrease of plasma NEFA concentrations and argue for a role of alpha 2-adrenoceptors in the NEFA mobilization from adipose tissue after sympathetic nervous system activation in man.
Barbe
P
P
INSERM U 317, Laboratoire de Pharmacologie Clinique et Médicale, Toulouse, France.
Galitzky
J
J
Riviere
D
D
Senard
J M
JM
Lafontan
M
M
Garrigues
M
M
Berlan
M
M
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D002395:Catecholamines / Q000097:blood; D003000:Clonidine / Q000494:pharmacology; D005230:Fatty Acids, Nonesterified / Q000097:blood*; D006801:Humans; D008297:Male; D009638:Norepinephrine / Q000097:blood; D011187:Posture / Q000502:physiology; D011311:Pressoreceptors / Q000187:drug effects; D012018:Reflex / Q000187:drug effects; D016683:Supine Position / Q000502:physiology; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology*; D015016:Yohimbine / Q000494:pharmacology
D001786:Blood Glucose; D002395:Catecholamines; D005230:Fatty Acids, Nonesterified; D015016:Yohimbine; D003000:Clonidine; D009638:Norepinephrine