Interleukin-6 production in human subcutaneous abdominal adipose tissue: the effect of exercise

Abstract

The interleukin-6 (IL-6) output from subcutaneous, abdominal adipose tissue was studied in nine healthy subjects before, during and for 3 h after 1 h two-legged bicycle exercise at 60 % maximal oxygen consumption. Seven subjects were studied in control experiments without exercise. The adipose tissue IL-6 output was measured by direct Fick technique. An artery and a subcutaneous vein on the anterior abdominal wall were catheterized. Adipose tissue blood flow was measured using the 133Xe-washout method. In both studies there was a significant IL-6 output in the basal state and no significant change was observed during exercise. Post-exercise the IL-6 output began to increase after 30 min. Three hours post-exercise it was 58.6 +/- 22.2 pg (100 g)(-1) min(-1). In the control experiments the IL-6 output also increased, but it only reached a level of 3.5 +/- 0.8 pg (100 g)(-1) min(-1). The temporal profile of the post-exercise change in the IL-6 output closely resembles the changes in the outputs of glycerol and fatty acids, which we have described previously in the same adipose tissue depot. The difference is that it begins to increase ~30 min before the glycerol and fatty acid outputs begin to increase. Thus, we suggest that the enhanced IL-6 production post-exercise in abdominal, subcutaneous adipose tissue may act locally via autocrine/paracrine mechanisms influencing lipolysis and fatty acid mobilization rate from this lipid depot.

Figure 1

Data are presented as means ± s.e.m. * Significant difference (P < 0.05) from the baseline (30 min) value. ○, the study including a 60 min exercise period. •, the control study without exercise. A, arterial plasma IL-6 concentrations. B, adipose venous-arterial (v-a) concentration differences calculated as venous – arterial plasma IL-6 concentrations. C, net release of IL-6 calculated as the product of the (v-a) concentration difference and adipose tissue plasma flow.

Figure 2

Subcutaneous, abdominal adipose tissue blood flow in the experiment with a 60 min exercise period (○), and in the control experiment without exercise (•).