Lactate dehydrogenase changes in diferent tissues in a chronical hypoxia adapted rat strain

We have previously shown that the maximal anaerobic power of highlander-bolivian children is more affected by their nutrition status rather than by altitude. To further link these observations to molecular measurements, lactate dehydrogenase (LDH) was studied in an animal model (Sprague Dawley rat strain) adapted to chronic hypoxia in La Paz (Bolivia, 3700 m, PB 5 490 mmHg). This strain food intakes are naturally 30 % reduced compared to “normoxic” animals. Then, two controls groups of low altitude-living rats were performed: one free fed (ad libitum) and another (pair-fed) nourished with the food intakes measured for the hypoxic group. The body weight growth curves were similar for both hypoxic and pair-fed groups. These observation remain unexplained although IGF-1 receptor mRNA levels exhibits variations. In white muscle, and right and left hearts, LDH specific activities drop dramatically in the pair-fed group compared to ad libitum one. This decreased which is partially compensated in chronic hypoxia conditions and this modifications cannot be explained by changes in the LDH isoenzyme patterns. This data support that anaerobic metabolism variations observed in altitude result in a confrontation of two mechanisms: hypoxia and reduced food intake.