Fig 1.

Exercise increases myocyte NOS1 expression, nitric oxide (NO) production and enhances myocyte contraction, which is normalized by acute NOS1 inhibition. A) Summary data of NOS1 protein expression (A.U.–arbitrary units), n=12 mice/group. B) Summary data of NO production over a 15 minute time period (±acute NOS1 inhibition, SMLT, dashed), n=19-26 cells/3 hearts. C) Representative traces of Ca²⁺ transients and shortening. Summary data of Ca²⁺ transient amplitudes (D), Ca²⁺decline to 50% of its peak (RT₅₀)(E), shortening amplitudes (F), and relengthening RT₅₀ (G) in exercise (Ex-grey) and sedentary (Sed-black)myocytes (±acute NOS1 inhibition, SMLT, striped), n=39-42 cells/7-10 hearts, (H) Summary data of Ca²⁺ transient (top) and shortening (bottom) amplitudes to various concentrations of ISO, n=12-39 myocytes/4 hearts, *P< 0.05 vs corresponding Sed.