In 35 controls (C: 18 f; 17 m; 19–43 yrs) and 14 newly diagnosed hypertensives (HTN: 4 f; 10 m; 23–58 yrs), skin blood flow in the palm of the hand and arterial pressure in a finger were recorded by laser Doppler and Finapres. Beat-to-beat mean pressure (MP), mean flow (MF) and resistance (R=MP/MF) were calculated in 5 min recordings.Temporal series were generated to perform FFT. Spectra were divided into VLF (0.02–0.04 Hz), LF (0.04–0.15) and HF (0.15–0.4) bands. Relative oscillatory power in each band was expressed as % of the total power in the three bands.

No difference in MP oscillatory power was found between HTN and C. MF power was higher in HTN than in C in the VLF band (m±se: 54,5 ±3,0% vs 39,5 ±2.6%; p<0,01), but lower in the LF band (39,8 ±2,7% vs 51,5±2,1%; p<0,01). Oscillatory power of R was also higher in HTN than in C in the VLF band (46,0 ±3,3% vs 34,5 ±3,1%; p<0.05), without significant difference in the LF band.

It has been suggested that VLF oscillations of MF and R are modulated by sympathetic activity. Wider VLF oscillations in HTN might be due to greater sympathetic oscillations or lesser dampening effect of endothelial factors. Oscillations in MF, but not in R, are less powerful in HTN in the LF band, whose periodicity has been suggested to depend on myogenic vascular rhythms, but also on sympathetic activity. This might be due to reduced myogenic activity in small vessels in HTN, and/or decreased sympathetic modulation by baroreflexes in the LF band.