Regional Differences In Gene Expression Profile In 2A Arterioles Isolated From Different Types Of Skeletal Muscle

Abstract

It has been previously shown that arterioles isolated from skeletal muscles of different fiber type composition or from different sections within the same skeletal muscle have distinct vasomotor responses to vasoactive agents involved in blood flow control. PURPOSE: To gain insights into potential determinants of these inhomogeneous vasomotor responsiveness the purpose of this study was to contrast and compare the transcriptional profile of isolated second order arterioles (2As) from the diaphragm (DIA) and red (RED) and white (WHITE) portion of gastrocnemius muscle of rats. METHODS: Twelve male Wistar rats were anesthetized and the gastrocnemius and diaphragm muscles were harvested and promptly placed in cold RNA stabilization reagent. A single 2A arteriole from each muscle section was carefully isolated, cleared of the surrounding muscle fibers and stored for analysis. Total RNA was extracted, reverse transcribed and amplified and the resulting cRNA was biotinylated and then hybridized to the Illumina® RatRef-12 Expression BeadChip (21,910 probes). RESULTS: Microarray analysis revealed that 202 gene elements were differentially expressed (1.5 fold difference) between RED and DIA. Genes involved in morphogenesis and tissue growth/development particularly exhibited different levels of expression between these two types of arteriole. In sharp contrast, only 11 genes showed more than 1.5 fold difference between WHITE and DIA. Of interest, the expression of alpha-1B adrenergic receptor was slightly higher in RED arterioles compared to DIA (1.25 fold, p=0.01) and WHITE (1.34 fold, p=0.002). Finally, the most marked distinct profile was found in the comparison between arterioles from the gastrocnemius muscle. Indeed, 435 genes, many linked to tissue morphogenesis and contraction, were found to be differentially expressed between RED and WHITE. We also found that the adenosine A2a receptor had a higher expression in RED vs. WHITE (1.33 fold, p=0.006). CONCLUSION: These observations demonstrate that substantial differences in the transcriptional profile exist between arterioles from different types of skeletal muscle. Of note, the greatest number of genes exhibiting different expression was observed from comparison of arterioles from different sections of the same muscle (RED vs. WHITE). Furthermore, the similarity between DIA and WHITE suggests that differences in global gene expression cannot be explained only by regional differences in fiber type composition and/or oxidative capacity. Support: NIH #HL36088 and Fulbright/ CAPES