Frequency response characteristic of sympathetic mediated low-frequency blood pressure fluctuations in conscious rats

• Published in: Autonomic neuroscience 2006-07, Vol.128 (1), p.48-52
• Main Authors: Chen, Ruei-Feng, Zeng, Wan-Ting, Yen, Chen-Tung, Tsai, Meng-Li
• Format: Article
• Language: English
• Subjects: Action Potentials - drug effects; Action Potentials - physiology; Adjuvants, Anesthesia - pharmacology; Animals; Arteries - innervation; Arteries - physiology; Biological and medical sciences; Blood pressure; Blood Pressure - drug effects; Blood Pressure - physiology; Conscious rat; Consciousness - physiology; Fourier Analysis; Fundamental and applied biological sciences. Psychology; Low-frequency fluctuation; Male; Muscle, Smooth, Vascular - innervation; Muscle, Smooth, Vascular - physiology; Pentobarbital - pharmacology; Peripheral nervous system. Autonomic nervous system. Neuromuscular transmission. Ganglionic transmission. Electric organ; Power spectral analysis; Rats; Rats, Wistar; Regression Analysis; Renal Artery - innervation; Renal Artery - physiology; Statistics as Topic - methods; Sympathetic Fibers, Postganglionic - drug effects; Sympathetic Fibers, Postganglionic - physiology; Sympathetic nerve activity; Vasoconstriction - drug effects; Vasoconstriction - physiology; Vertebrates: nervous system and sense organs
• ISSN: 1566-0702; 1872-7484
• DOI: 10.1016/j.autneu.2006.02.001

A quantitative relationship between power densities of blood pressure ( P BP) and sympathetic nerve activity ( P SNA) in a low-frequency range (LF, 0.016–0.85 Hz), expressed as P SNA = P BP × a × 10 b×(frequency) was proposed in pentobarbital-anesthetized rats. For evaluating the general applicability of this equation, the quantitative relationship of power density ratio H( f) = P BP/ P SNA across frequency was tested in a conscious state. Wistar rats were chronically instrumented with a femoral artery catheter and recording electrode around the renal sympathetic nerve. The blood pressure and renal sympathetic nerve activity were monitored both under pentobarbital anesthesia and in a conscious state. Linear regression analysis of the relationship between the frequency and logarithmic magnitude of the power density ratio in the LF range revealed excellent fit in both conditions ( r = − 0.96 ± 0.01 and − 0.93 ± 0.01 for anesthetized and conscious rats, respectively). Comparing the regression lines, rats under pentobarbital anesthesia had significantly larger values for the y-intercept and slope compared to rats in a conscious state ( y-intercepts: 0.80 ± 0.09 > 0.53 ± 0.08; slopes: − 2.86 ± 0.26 > − 1.62 ± 0.21). Our results demonstrate that it is also feasible to use the weighted P BP in LF as a quantitative index of sympathetic variability in conscious rats, but the evaluation of possible complications controlling the regression parameters is called for.