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Effects of local α 2 ‐adrenergic receptor blockade on adipose tissue lipolysis during prolonged systemic adrenaline infusion in normal man
Author(s) -
Simonsen Lene,
Enevoldsen Lotte H.,
Stallknecht Bente,
Bülow Jens
Publication year - 2008
Publication title -
clinical physiology and functional imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.608
H-Index - 67
eISSN - 1475-097X
pISSN - 1475-0961
DOI - 10.1111/j.1475-097x.2007.00781.x
Subject(s) - lipolysis , adipose tissue , phentolamine , endocrinology , medicine , microdialysis , stimulation , adrenergic , white adipose tissue , receptor , dopamine
Summary During prolonged adrenaline infusion, lipolysis peaks within 30 min and thereafter tends to decline, and we hypothesized that the stimulation of local adipose tissue α 2 ‐adrenergic receptors accounts for this decline. The lipolytic effect of a prolonged intravenous adrenaline infusion combined with local infusion of the α 2 ‐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 α 2 ‐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 α 2 ‐adrenergic receptor inhibition of lipolysis. However, in the preperitoneal adipose tissue depot, α 2 ‐adrenergic receptor tone plays a role for the lipolytic rate obtained during prolonged adrenaline stimulation.