Regional difference in lipolysis caused by a β‐adrenergic agonist as determined by the microdialysis technique

Abstract

We have investigated the difference in lipolysis caused by a beta-adrenergic agent between visceral and abdominal subcutaneous adipose tissues in vivo. Glycerol levels (lipolysis index) were continuously monitored in mesenteric and abdominal subcutaneous adipose tissues of anaesthetized Wistar rats using the microdialysis technique. During microdialysis, increasing concentrations of the lipolytic agent, isoproterenol (10(-8), 10(-7), 10(-6), 10(-5) mol L-1), were added to the perfusion. Glycerol concentrations in dialysate at each isoproterenol concentration, blood glucose concentrations during the experiment, and plasma insulin concentrations before and immediately after the experiment were measured. The effect of isoproterenol on local blood flow was investigated using the ethanol technique. The clearance rate of ethanol from the perfusion medium was used as the index of local blood flow. There was no significant change in blood glucose or plasma insulin concentrations during the study. Glycerol levels in dialysate were significantly higher in mesenteric than in abdominal subcutaneous adipose tissues at all isoproterenol concentrations. The percentage change of baseline ethanol ratio was not altered by increasing isoproterenol concentrations in both mesenteric and subcutaneous adipose tissues. There was also no significant difference in percentage change of the baseline ethanol ratio between mesenteric and abdominal subcutaneous adipose tissues. These results suggest that mesenteric adipose tissue is characterized by an even higher beta-adrenergic agonist-induced lipolysis than abdominal subcutaneous adipose tissue.

Selective Fatty Acid Mobilization from Adipose Tissues of the Pheasant (Phasianus colchicus mongolicus) during Food Deprivation

“…At tbe end of food deprivation on December 21 between 1200 and 1400 hours, the birds were anesthetized with intramuscular ketamine and xylazine and euthanized with intracardial embutramide, mebezonium iodide, and tetracaine bydrochloride. Samples were taken from the liver and from the IAB (mesenteric) and SC (flank) fat tissues because the rates of lipolysis differed between these adipose tissue sites in mammals (Iwao et al 1997). All samples were frozen in liquid nitrogen and stored at -80"C.…”

Adipose Tissue: A Metabolic Regulator. Potential Implications for the Metabolic Outcome of Subjects Born Small for Gestational Age (SGA)

“…No data on SGA subjects isoproterenol concentrations, while basal lipolysis was identical in the two depots [94]. Omental fat has been reported to be relatively resistant to insulin suppression of lipolysis in vitro and sensitive to β3-adrenergic stimulation of lipolysis [95].…”

Effects of obesity phenotype on fat metabolism in obese men during endurance exercise

“…[2][3][4][5] These metabolic abnormalities are associated with the characteristics of visceral adipocytes. Previous in vitro studies in humans [6][7][8][9][10] have provided data that lipolytic responses to catecholamines of visceral adipocytes are 1.5-3.0 times higher than subcutaneous ones. Furthermore, it has been reported that visceral adipocytes have a lower antilipolytic response to insulin 7,11 than subcutaneous adipocytes.…”