Abstracts: American College of Sports Medicine Conference on Integrative Physiology of Exercise: SATURDAY, SEPTEMBER 30, 2006: POSTER SESSION 3: Metabolic
Obesity is a serious condition defined by excess body fat which may contribute to serious health concerns such as Type 2 diabetes, coronary artery disease, and dylipidemia. Nitric oxide (NO) has been shown to inhibit lipolysis and obese individuals tend to have more nitric oxide synthase (NOS) content in adipose tissue compared to lean.
It was the purpose of this study to evaluate the effects of NO on regional lipolysis in obese women before and after ten days of aerobic exercise training.
An index of lipolysis, from dialysate glycerol concentration and nutritive flow measures, was obtained using the microdialysis technique. Three probes were inserted into the abdominal subcutaneous adipose tissue (AAT) and femoral subcutaneous adipose tissue (FAT). Resting lipolysis was evaluated under non-stimulated, and NOS inhibited (LNMMA) conditions. Participants exercised on a cycle ergometer for an hour per day for ten days.
Dialysate glycerol did not change in response to exercise training in the AAT (100.6±14.7 μM PRE; 125.71±26.6 μM POST) or FAT (123.9±9.7 μM PRE; 135.8±21.8 μM POST). In AAT, dialysate glycerol concentration was higher with NOS inhibition than in the non-stimulated control probe before (160.1±26.8 μM LNMMA; 102.3±7.7 μM CON; p<0.05) and after (184.6±31.9 μM LNMMA; 114.2±16.3 μM CON; p<0.05) training. In FAT, NO suppressed resting lipolysis before (201.1±29.9 μM LNMMA; 140.9±14.4 μM CON; p<0.05) but not after (156.2±26.4 μM LNMMA 118.1±11.5 μM CON, p<0.05) training compared to the control probe.
We found that exercise training did not alter resting, non-stimulated lipolysis. When NOS was inhibited by L-NMMA, lipolysis increased in AAT compared to the control probe before and after exercise training. However, in FAT, lipolysis increased with NOS inhibition before, but not after, exercise training compared to the control probe indicating that exercise training may decrease NO production in FAT. Our results indicate that ten days of exercise does not provide enough stimulus to alter non-stimulated lipolysis, but may alter the NOS regulation of lipolysis, in obese women.