Figure 3: Effects of Chronic VNS on Power Spectral Density of Heart Rate, Hemodynamic Variables, and Plasma BNP

Values are mean ± SEM. Differences were tested by using 1-way analysis of variance, followed by post hoc Tukey-Kramer tests. ∗p < 0.05 and ∗∗p < 0.01 vs. CTRL. †p < 0.05 and ‡p < 0.01 vs. SS. (A) Representative traces of power spectral density of heart rate in CTRL, SS, and VNS in rats at 5 weeks after SU5416 injection. The frequency range of 0.04–0.73 Hz was defined as low frequency (LF) and 0.73–2.0 Hz as high frequency (HF). The HF of HRV that represents parasympathetic nerve activity is lower in SS than CTRL but is higher in VNS than in SS. (B to G) Mean pulmonary arterial pressure (mPAP), pulmonary vascular resistance (PVR), cardiac index (CI), right ventricular end-diastolic pressure (RVEDP), and maximum first derivation of right ventricular pressure normalized by RVEDP (Max +dP/dt/RVEDP) are shown. VNS significantly reduces mPAP and improves right ventricular function. CTRL, n = 5; SS, n = 6; and VNS, n = 6. BNP = brain natriuretic peptide; other abbreviations as in Figure 2.