TY - JOUR

T1 - Effects of local alpha2-adrenergic receptor blockade on adipose tissue lipolysis during prolonged systemic adrenaline infusion in normal man

AU - Simonsen, Lene

AU - Enevoldsen, Lotte H

AU - Stallknecht, Bente

AU - Bülow, Jens

N1 - Keywords: Adrenergic alpha-Antagonists; Adult; Epinephrine; Humans; Infusions, Intravenous; Lipolysis; Male; Microdialysis; Phentolamine; Regional Blood Flow; Subcutaneous Fat, Abdominal

PY - 2008

Y1 - 2008

N2 - During prolonged adrenaline infusion, lipolysis peaks within 30 min and thereafter tends to decline, and we hypothesized that the stimulation of local adipose tissue alpha2-adrenergic receptors accounts for this decline. The lipolytic effect of a prolonged intravenous adrenaline infusion combined with local infusion of the alpha2-blocker phentolamine in superficial and deep abdominal subcutaneous adipose tissue and in preperitoneal adipose tissue was studied in seven healthy subjects. The interstitial glycerol concentration in the three adipose tissue depots was measured by the microdialysis method. Regional adipose tissue blood flow was measured by the (133)Xe clearance technique. Regional glycerol output (lipolytic rate) was calculated from these measurements and simultaneous measurements of arterial glycerol concentrations. Adrenaline infusion increased lipolysis in all three depots (data previously published). Phentolamine infusion did not augment lipolysis in the subcutaneous depots while it increased the lipolytic rate in the preperitoneal depot. It is concluded that alpha2-adrenergic receptors do not have a significant effect on subcutaneous adipose tissue lipolysis during high circulating adrenaline concentrations, and the decrease in lipolysis in subcutaneous adipose tissue under prolonged adrenaline stimulation is thus not attributed to alpha2-adrenergic receptor inhibition of lipolysis. However, in the preperitoneal adipose tissue depot, alpha2-adrenergic receptor tone plays a role for the lipolytic rate obtained during prolonged adrenaline stimulation.

AB - During prolonged adrenaline infusion, lipolysis peaks within 30 min and thereafter tends to decline, and we hypothesized that the stimulation of local adipose tissue alpha2-adrenergic receptors accounts for this decline. The lipolytic effect of a prolonged intravenous adrenaline infusion combined with local infusion of the alpha2-blocker phentolamine in superficial and deep abdominal subcutaneous adipose tissue and in preperitoneal adipose tissue was studied in seven healthy subjects. The interstitial glycerol concentration in the three adipose tissue depots was measured by the microdialysis method. Regional adipose tissue blood flow was measured by the (133)Xe clearance technique. Regional glycerol output (lipolytic rate) was calculated from these measurements and simultaneous measurements of arterial glycerol concentrations. Adrenaline infusion increased lipolysis in all three depots (data previously published). Phentolamine infusion did not augment lipolysis in the subcutaneous depots while it increased the lipolytic rate in the preperitoneal depot. It is concluded that alpha2-adrenergic receptors do not have a significant effect on subcutaneous adipose tissue lipolysis during high circulating adrenaline concentrations, and the decrease in lipolysis in subcutaneous adipose tissue under prolonged adrenaline stimulation is thus not attributed to alpha2-adrenergic receptor inhibition of lipolysis. However, in the preperitoneal adipose tissue depot, alpha2-adrenergic receptor tone plays a role for the lipolytic rate obtained during prolonged adrenaline stimulation.

U2 - 10.1111/j.1475-097X.2007.00781.x

DO - 10.1111/j.1475-097X.2007.00781.x

M3 - Journal article

C2 - 18076658

VL - 28

SP - 125

EP - 131

JO - Clinical Physiology and Functional Imaging

JF - Clinical Physiology and Functional Imaging

SN - 1475-0961

IS - 2

ER -