Chronic hypoxia changes gene expression profile of primary rat carotid body cells: consequences on the expression of NOS isoforms and ET-1 receptors.

Sustained chronic hypoxia (CH) produces morphological and functional changes in the carotid body (CB). Nitric oxide (NO) and endothelin-1 (ET-1) plays a major role as modulators of the CB oxygen chemosensory process. To characterize the effects of CH related to normoxia (Nx) on gene expression, particularly on ET-1 and NO pathways, primary cultures of rat CB cells were exposed to 7 days of CH. Total RNA was extracted, cDNA-32 P synthesized and hybridized with 1185 genes printed on a nylon membrane Atlas cDNA Expression Array. Out of 324 differentially expressed genes, 184 genes were up-regulated, while 140 genes were down-regulated. The cluster annotation and protein network analyses showed that both NO and ET-1 signalling pathways were significantly enriched and key elements of each pathway were differentially expressed. Thus, we assessed the effect of CH at the protein level of NOS isoforms and ET-1 receptors. CH induced an increase in the expression of eNOS, iNOS and ETB . During CH, the administration of SNAP, a NO-donor, upregulated ETB . The treatment with Tezosentan (ET-1 receptor blocker) during CH up-regulated all three NOS isoforms, while the NOS blocker L-NAME induced up-regulation of iNOS and ETB and down-regulated the protein levels of ETA . These results showed that CH for 7 days changed the cultured cells CB gene expression profile, the NO and ET-1 signaling pathways were highly enriched and these two signaling pathways interfered on the protein expression of each other.