Similarly, insulin’s muscle microvascular actions are blunted in animal models of obesity or diabetes [67,69], and the loss of muscle microvascular insulin responses is also apparent in healthy rodents with acute experimental insulin resistance conferred by systemic infusions of factors known to be elevated in the insulin resistant states, such as tumor necrosis factor α (TNF-α) [70] and FFAs [71]. This evidence concerns the gene TNF and obesity due to melanocortin 4 receptor deficiency.