Vasoreactivity of aortic rings. a Wire myography showed no difference in U46619-induced vasoconstriction among the three mouse strains. However, in comparison to 129S and B6/129S mice, C57Bl/6J mice had the greatest alpha-1-dependent vasoconstrictive response to phenylephrine (b) and the lowest maximum contractile response to potassium chloride (KCl) (c). Similarly there was no difference in the nitric endothelium-independent response to sodium nitroprusside (SNP) (d), but C57Bl/6J did show a much more robust nitric oxide-dependent response to acetylcholine (Ach) (e). (n = 10 per group, P < 0.001 for 129S vs. C57Bl/6J, 129S vs. B6/129S, and C57Bl/6J vs. B6/129S)