Effects of local α₂-adrenergic receptor blockade on adipose tissue lipolysis during prolonged systemic adrenaline infusion in normal man

Authors: Simonsen, Lene¹; Enevoldsen, Lotte H.²; Stallknecht, Bente³; Bülow, Jens¹

Source: Clinical Physiology and Functional Imaging, Volume 28, Number 2, March 2008 , pp. 125-131(7)

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Abstract:

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 α₂-adrenergic receptors accounts for this decline. The lipolytic effect of a prolonged intravenous adrenaline infusion combined with local infusion of the α₂-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 ¹³³Xe 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 α₂-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 α₂-adrenergic receptor inhibition of lipolysis. However, in the preperitoneal adipose tissue depot, α₂-adrenergic receptor tone plays a role for the lipolytic rate obtained during prolonged adrenaline stimulation.

Keywords: abdominal superficial subcutaneous adipose tissue; blood flow; gluteal deep subcutaneous adipose tissue; microdialysis, phentolamine; preperitoneal adipose tissue

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1475-097X.2007.00781.x

Affiliations: 1: Department of Clinical Physiology, Bispebjerg Hospital, Copenhagen 2: Department of Clinical Physiology, Herlev Hospital, Herlev 3: Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Copenhagen, Denmark

Publication date: 2008-03-01