Effect of food restriction on lactate sarcolemmal transport.

The objective of this study was to investigate the effects of 6 weeks of food restriction (FR) on sarcolemmal lactate transport in rats. The daily food consumption of rats was monitored for 10 days, after which they were assigned to either a control group (CTL, n = 7) that consumed food ad libitum or an FR group (n = 7) that received a daily ration equal to 60% of their predetermined baseline food intake. After the 6-week period, we observed in red gastrocnemius (RG) a fall of 48% in glycogen content (P <.01) and a reduction in glutathione peroxidase activity (P <.05), confirming that the FR program was well executed. FR resulted in a reduction in muscle lactate (P <.05) and liver glycogen contents (P <.01). Moreover, hyperlactatemia was noted in the FR group: 1.77 +/- 0.24 versus 2.67 +/- 0.29 mmol/L (P <.05). Lactate transport capacity was significantly increased (P <.05) in FR rats, although monocarboxylate transporter isoforms (MCT1 and MCT4) did not change significantly. We conclude that FR alters sarcolemmal lactate transport activity without affecting MCT1 and MCT4 expression.