Adaptations of lactate metabolism in iron-deficient rats.

Effects of dietary iron deficiency on lactate metabolism were studied in weanling female rats. Following an iron-deficient diet for 5 weeks, mean hemoglobin concentration was lowered to 6.4 g/dl relative to 12.2 in the control group. Mean plasma iron levels were 58 and 162 micrograms/dl, respectively. Significantly elevated resting lactate levels were observed in whole blood and plasma from iron-deficient anemic (relative to control) rats. Total activity of lactate dehydrogenase (LDH) was elevated in soleus and gastrocnemius muscles in response to iron deficiency from 269 +/- 51 to 364 +/- 60 (Mean +/- SD) and from 265 +/- 65 to 372 +/- 61 IU . 10(-3) . g-1, respectively. The LDH activity in heart was lowered from 700 +/- 61 to 593 +/- 45 IU . 10(-3) . g-1. The M3H and M2H2 isozymes in soleus were increased from 12.7 +/- 2.8 to 20.4 +/- 5.8% and from 19.4 +/- 6.1 to 28.2 +/- 3.6%, respectively. Similar increase was observed in M2H2 and MH3 in gastrocnemius from 9.8 +/- 0.9 to 14.8 +/- 2.0% and from 17.4 +/- 2.0 to 20.5 +/- 2.3%, respectively. The H4 isozyme was significantly reduced in soleus, gastrocnemius, and plantaris muscles from 27.7 +/- 4.7 to 12.4 +/- 4.4, from 15.8 +/- 1.9 to 7.2 +/- 2.9, and from 10.5 +/- 2.9 to 3.9 +/- 2.1%, respectively. It was suggested that iron-deficiency anemia induces an elevation of lactate production following an increase in total LDH activity and change in LDH isozyme patterns.