Does low frequency power of arterial blood pressure reflect sympathetic tone?
We tested whether power spectral analysis of arterial blood pressure (ABP) is a feasible tool to detect differences in peripheral sympathetic nerve activity in normotensive and hypertensive rats with differing basal sympathetic tones. Nine Wistar Kyoto rats (WKY), 10 Sprague-Dawley rats (SD), 10 spontaneously hypertensive rats (SHR) and 9 hypertensive transgenic rats harbouring the mouse Ren-2 gene (TGR) were chronically instrumented with femoral artery catheters and nerve electrodes around the sympathetic major splanchnic nerve. Two days after surgery ABP and splanchnic nerve activity (SpNA) were recorded in the conscious state during basal conditions as well as during alpha 1-adrenergic receptor blockade. Power spectra and squared coherence in the low (LF, 0.02-0.20 Hz), mid (MF, 0.20-0.80 Hz) and high (HF, respiration peak +/- 0.3 Hz) frequency bands were calculated for ABP and SpNA. Mean blood pressure in SHR (133 +/- 8 mmHg) and TGR (142 +/- 8 mmHg) was significantly higher (P < 0