PFK activity in muscle and heart tissue is differentially affected by dietary restriction

This research examined the effect of dietary restriction on PFK activity (one of the enzymes in the glycolytic pathway) in selected skeletal and heart muscle tissue. Fifty-five Sprague-Dawley female rats were separated into three different groups for 10 weeks of dietary restriction: AL = ad lib fed, MR = weight reduced to 81% of AL and SR = weight reduced to 63% of AL. Gastrocnemius white (GW), plantaris, soleus (S) and heart (H) muscle tissue were dissected out and assayed for PFK activity. PFK activity (mumole/g/min) in GW was 105 +/- 7, 86 +/- 6 and 61 +/- 6 for AL, MR & SR, respectively (AL > MR > SR, P < 0.05). PFK activity in S was 25 +/- 2, 22 +/- 1 and 16 +/- 1 for AL, MR and SR, respectively (AL, MR > SR, P < 0.05). In contrast, PFK activity in H was unaffected (P > 0.05). These data suggest that PFK activity in various muscle tissues is differentially affected during diet-induced weight loss.