Investigate The Underlying Mechanisms of Cold-Induced Hemodynamic Oscillations in Conscious Rats Via Spectrum Analysis.

• Main Authors: Yu-Chieh Lin, 林鈺傑
• Other Authors: Che-Se Tung
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/10354182252947735097

碩士 === 國防醫學院 === 生理學研究所 === 103 === Evidence has demonstrated that proper blood pressure variability (BPV) and heart rate variability (HRV)is important for health. By using the spectral analysis of systolic blood pressure and BPV, we examined the influence of sympathetic activity on the change of cardiovascular responses (CVR) of rats during stressful cold impact (CI). We used two different sympathectomized drugs: Hexamethonium (HEX), a ganglion blocker, or Guanethidine (GUA), a chemical sympathectomy agent, to reduce the release of norepinephrine (NE) in SD Rats. Animals were injected HEX or GUA before they were immersed in iced water for 10 min. CVR was monitored continuously via a telemetric device before, after, and during the 10 min of CI trial. Systolic blood pressure (SBP), Heart rate (HR), Variance of SBP, HR variability (HRV), and specific spectrum of BPV (including VLF and nLF) were obtained by telemetric system (Data Sciences International, DSI). Peripheral administration of Yohimbine (an α2 adrenoceptor antagonist), CGRP8-37 or Vasopressin antagonist (VAS) were applied as pharmacological intervention, to see the possible interactions with HEX and GUA. Our results showed that CI per se resulted in tachycardia, increased BP, and concomitantly with the increased nLF . The BPV effect was diminished after the administration of HEX, with the effects on SBP and HR preserved. In GUA administered rats, SBP and HR were reduced significantly, but the sympathetic driving activity (reflected by nLF) still existed. On the other hand, the CI-induced vascular oscillations were significant reduced in HEX group after administration of YOH. We found that sympathetic driving activity would be changed when animal was challenged with CI, and α2 adrenoceptor may play an important role of sympathetic influences on vascular oscillations. The results of GUA and HEX data prompt us to investigate other factors causing the change of CI, such as the sensory nerve afferent pathway at dorsal root ganglion (Dorsal root ganglion, DRG).