With the use of the microdialysis method, exercise-induced lipolysis was investigated in subcutaneous adipose tissue (SCAT) in obese subjects and compared with lean ones, and the effect of blockade of alpha(2)-adrenergic receptors (ARs) on lipolysis during exercise was explored. Changes in extracellular glycerol concentrations and blood flow were measured in SCAT in a control microdialysis probe at rest and during 60-min exercise bouts (50% of heart rate reserve) and in a probe supplemented with the alpha(2)-AR antagonist phentolamine. At rest and during exercise, plasma norepinephrine and epinephrine concentrations were not different in obese compared with lean men. In the basal state, plasma and extracellular glycerol concentrations were higher, whereas blood flow was lower in SCAT of obese subjects. During exercise, the increase of plasma glycerol was higher in obese subjects (115 +/- 35 vs. 65 +/- 21 micromol/l). Oppositely, the exercise-induced increase in extracellular glycerol concentrations in SCAT was five- to sixfold lower in obese than in lean subjects (50 +/- 14 vs. 318 +/- 53 micromol/l). The exercise-induced increase in extracellular glycerol concentration was not significantly modified by phentolamine infusion in lean subjects but was strongly enhanced in the obese subjects and reached the concentrations found in lean sujects (297 +/- 46 micromol/l). These findings demonstrate that the physiological stimulation of SCAT adipocyte alpha(2)-ARs during exercice-induced sympathetic nervous system activation contributes to the blunted lipolysis noted in obese men.

Patients with hypertension exhibit reduced heart rate control during the recovery period after elective surgery. Clonidine prevents this reduction in heart rate control. This may represent a basis for the improved circulatory stability seen with perioperative administration of clonidine.

The hormonal response to undernutrition is heterogeneous in a large population with restrictive AN. In clinical practice, metanephrines, GH, and/or cortisol data could be used as important predictors for severe short-term outcome.

The effect of chronic hypoxia on gender differences in physiology and neurochemistry of chemosensory pathways was studied in prepubertal and adult rats living at sea level (SL; Lyon, France) or at high altitude (HA; La Paz, Bolivia, 3,600 m). HA adult rats had higher hematocrit (Ht%), Hb concentration, resting ventilatory rate (Ve(100)), and higher tyrosine hydroxylase (TH) activity in carotid bodies (CB) than SL animals. At HA and SL, adult females had lower Ht% (46.0 +/- 0.8 vs. 50.4 +/- 0.6% at HA, P < 0.05 and 43.8 +/- 0.9 vs. 47.1 +/- 0.8% at SL, P < 0.05) and Hb (16.1 +/- 0.3 vs. 17.7 +/- 0.2 g/dl at HA, P < 0.05 and 14.5 +/- 0.3 vs. 15.6 +/- 0.1 g/dl at SL, P < 0.05) than males. Females had higher Ve(100) [170 +/- 19 vs. 109 +/- 7 ml. min(-1). 100 g(-1) at HA, P < 0.05 and 50 +/- 3 vs. 40 +/- 2 ml. min(-1). 100 g(-1) at SL, not significant (NS)] and lower CB-TH activity (1.40 +/- 0.2 vs. 3.87 +/- 0.6 pmol/20 min at HA, P < 0.05 and 0.52 +/- 0.1 vs. 0.68 +/- 0.1 pmol/20 min at SL; NS) than males at HA only. The onset of hypoxic ventilatory response during development was delayed at HA. Prepubertal HA females had higher Ve(100) than males (2 wk old, +47%) and higher CB-TH activity (3 wk old, +51%). Medullary noradrenergic groups were sex dimorphic during development at SL. Rats raised at HA had a drop of TH activity between the second and the third postnatal week in all medullary groups. In conclusion, our data support the hypothesis that the CB is the major site for sexual differentiation of the ventilatory control. Ventilatory differences appeared before puberty, and the animals bred at HA had profound alterations in the developmental process of the chemoreflex and its neural pathways. Some of these alterations are under dependence of the sex of the animal, and there is an important interaction between gender and the hypoxic environmental condition during the developmental period.