Two ranges in blood pressure power spectrum with different 1/f characteristics.
Most time series of biological systems contain a considerable amount of 1/f noise. This form of noise is characterized by fluctuations in which power steadily increases at lower frequencies. To determine the origin of 1/f noise, blood pressure (BP) was measured over 4 h in conscious foxhounds. The power spectrum of BP was obtained by fast Fourier analysis. After log-log transformation, the power spectrum (log power vs. log frequency) characteristically revealed a linear regression. Surprisingly, there were two 1/f ranges. The first 1/f region was located within a low-frequency range (< 10(-1.7) Hz; slope -0.9; r = -0.9). The second 1/f range was identified at 10(-1.4) to 10(-1) Hz (slope -1.2; r = -0.7). After baroreceptor denervation (n = 7), the steepness of both slopes increased significantly (P < 0.05 for lower 1/f range, P < 0.001 for higher 1/f range), and the difference in slopes was clearly greater (slope in lower range -1.2; r = 0.96 vs. -3.1, r = -0.92 in the higher range; P < 0.001). Neither alpha-receptor (n = 6) nor beta-receptor blockade (n = 4) considerably changed the slopes after denervation. However, autonomic blockade (n = 5) restored the slope in the low-frequency range (-0.9; r = -0.9). In conclusion, there are two independently modulated 1/f frequency ranges in BP time series. Baroreceptors especially attenuate 1/f noise in the higher frequency range.
Wagner
C D
CD
I. Physiologisches Institut der Ruprecht-Karis, Universitat Heidelberg, Germany.
Persson
P B
PB
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D003714:Denervation; D004285:Dogs; D005260:Female; D005583:Fourier Analysis; D005730:Ganglionic Blockers / Q000494:pharmacology; D006339:Heart Rate; D018738:Hexamethonium; D006584:Hexamethonium Compounds / Q000494:pharmacology; D008297:Male; D011224:Prazosin / Q000494:pharmacology; D011311:Pressoreceptors / Q000502:physiology; D012044:Regression Analysis
D005730:Ganglionic Blockers; D006584:Hexamethonium Compounds; D018738:Hexamethonium; D011224:Prazosin