Skeletal muscle transcriptional adaptions to hypoxia and maximal exercise

Hypoxic conditions and maximal exercise provide related but distinct energetic stresses for muscle tissue and induce different adaptations in skeletal muscle in mammals. High swim performance fish, including Danio Rerio (Zebrafish), are well-able to tolerate both hypoxia and fast swimming. Expression profiling was performed using microarrays to compare and contrast the adaptations to sustained hypoxia and repeated near maximal exercise in skeletal muscle of adult wild-type Zebrafish. Four conditions were studied: control (a) normoxia (20kPa O2) + spontaneous swimming; (b) normoxia (20kPa O2) and high swim exercise (35 cm/sec) for 6hrs per 24 hrs; (c) hypoxia (6kPa O2) + high swim exercise (30 cm/sec) for 6hrs per 24hrs; (d) hypoxia (4kPa O2) + low swim exercise (7 cm/s). Fish were kept under test conditions for 5 days in a shoal of up to 8. Total RNA was extracted from post-anal muscle block from each fish and equal quantities of high-quality RNA from 2-3 fish from each experiment were pooled. 16 pooled samples were formed and applied to separate arrays representing 4 independent experimental replicates of each of the 4 experimental conditions.