Although expression of Kv1.2, Kv2.1, Kv3.1, and Kv9.3 p-Tyr increased in IUGR-hypoxia groups compared to control-hypoxia groups, only Kv1.5 α-protein levels decreased more significantly than the mRNA decreased, indicating that the Kv1.5 channel is more sensitive than other Kv channels to the role of tyrosine phosphorylation. This evidence concerns the gene KCNA5 and hypoxia.