Exercise attenuates the anti-lipolytic effect of adenosine in adipocytes isolated from miniature swine.
Four pairs of female and six pairs of male litter-mate Yucatan miniature swine (Sus scrofa) were used in this study which examined the possibility that endurance exercise training reduces the sensitivity of adipocytes to the anti-lipolytic effects of adenosine. One member of each pair was exercise-trained on a treadmill for three months while its litter-mate remained sedentary, after which time over-the-shoulder fat and left brachialis muscle were biopsied. Despite a predominance of type IIB fibres, biopsied muscle of exercised swine had 38% more citrate synthase activity than controls (P < 0.05). The average cell diameters of adipocytes isolated from exercisers were 14% smaller (P < 0.05) than those from controls. Rates of adrenaline-stimulated lipolysis expressed as nmol glycerol released/90 min incubation period per 10,000 cells failed to differ between the two groups; however, when expressed per cm2 surface area, a significant 37% increase was observed. Incubation with 1 microM adrenaline and increasing doses of phenylisopropyladenosine (PIA) caused a rightward shift in the dose-response curve of adipocytes in five of the ten exercisers compared to litter-mate controls. The concentration of PIA causing one-half inhibition of lipolysis was 64% greater in adipocytes from exercisers than controls (4.03 nM vs. 2.49 nM, n = 10, P < 0.05). These data support the hypothesis that endurance exercise-training induces a reduction in adipocyte sensitivity to adenosine, thereby facilitating fatty acid mobilization.
Carey
G B
GB
Department of Animal & Nutritional Sciences, University of New Hampshire, Durham 03824.
Sidmore
K A
KA
D000241:Adenosine / Q000494:pharmacology*; D017667:Adipocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D002950:Citrate (si)-Synthase / Q000378:metabolism; D005260:Female; D005990:Glycerol / Q000378:metabolism; D008066:Lipolysis / Q000187:drug effects*; D008297:Male; D009132:Muscles / Q000378:metabolism; D010660:Phenylisopropyladenosine / Q000494:pharmacology; D010805:Physical Conditioning, Animal; D010807:Physical Endurance; D005082:Physical Exertion; D013552:Swine; D013556:Swine, Miniature
D010660:Phenylisopropyladenosine; D002950:Citrate (si)-Synthase; D000241:Adenosine; D005990:Glycerol