Fig. 2.

Effects of nitrite on the components of the CI in nonhemolyzing animals. The CI (A) and its components (B) were transformed into the log scale to demonstrate the individual contribution of heart rate (HR) and stroke volume index (SVI) to CI in an additive fashion (normal scale: CI = SVI × HR, log scale: log CI = log SVI + log HR) (68). In animals receiving D5W and nitrite, the nitrite-induced increase in the CI is mediated predominantly through an increase in SVI and to a lesser extent by a chronotropic effect. Over time, the decrease in HR causes further increases in SVI by increasing diastolic filling time in the ventricles, leading to higher end-diastolic volumes. Furthermore, the higher end-diastolic volumes translate into higher end-diastolic pressures, which may explain the increase in PAOP over time (Fig. 1H).