Figure 2 Forearm blood flow responses before and after CPAP showing significantly enhanced responses to ACh alone or ACh with l‐NMMA after CPAP than before (p<0.001). SNP responses were unchanged with CPAP treatment. The vasoconstrictor response to l‐NMMA was significantly greater after CPAP than before (p = 0.05), consistent with an enhanced release of nitric oxide from the vascular endothelium.