Title :
Very Low Frequency Modulation in Renal Autoregulation
Author :
Siu, Kin L. ; Sung, Biin ; Moore, Leon C. ; Birzgalis, Aija ; Chon, Ki H.
Author_Institution :
Biomed. Eng., SUNY, Stony Brook, NY
fDate :
Aug. 30 2006-Sept. 3 2006
Abstract :
This study aims to examine the presence of a possible third renal autoregulatory mechanism in the very low frequency (VLF) band (~10 mHz) using a high-resolution time- frequency spectral method. Blood pressure and renal blood flow data were measured from conscious and anesthetized Sprague-Dawley and spontaneously hypertensive rats, at the level of the whole kidney (via ultrasound flow probe) and local cortical tissue of a kidney (via laser Doppler flow probe). In addition, N-nitro-L-arginine (LNAME) was used in order to assess the effect of nitric oxide on the third mechanism. Using a complex demodulation method with high time and frequency resolution, a VLF band was often observed, as well as amplitude modulation at the VLF of the two other autoregulation mechanisms. The presence of amplitude modulation is an indication of a particular form of nonlinear interaction between the autoregulatory mechanisms. Physically, such interactions may arise from the fact that all three mechanisms share a common effector, the afferent arteriole. In addition, the magnitude of amplitude modulation of the VLF on the other autoregulatory mechanisms was enhanced by the addition of LNAME, suggesting an important role of nitric oxide in the autoregulatory process
Keywords :
Doppler measurement; biomedical ultrasonics; blood flow measurement; blood pressure measurement; blood vessels; kidney; laser applications in medicine; nitrogen compounds; organic compounds; probes; time-frequency analysis; N-nitro-L-arginine; Sprague-Dawley rats; afferent arteriole; blood pressure measurement; complex demodulation method; frequency resolution; high-resolution time-frequency spectral method; kidney; laser Doppler flow probe; local cortical tissue; nitric oxide; renal autoregulatory mechanism; renal blood flow measurement; spontaneously hypertensive rats; ultrasound flow probe; very low frequency modulation; Amplitude modulation; Blood flow; Blood pressure; Fluid flow measurement; Frequency modulation; Hypertension; Pressure measurement; Probes; Rats; Ultrasonic variables measurement;
Conference_Titel :
Engineering in Medicine and Biology Society, 2006. EMBS '06. 28th Annual International Conference of the IEEE
Conference_Location :
New York, NY
Print_ISBN :
1-4244-0032-5
Electronic_ISBN :
1557-170X
DOI :
10.1109/IEMBS.2006.259620