- 期刊
腦幹調控血壓之動態性質
Dynamic Regulation of Arterial Blood Pressure from the Brainstem
摘要
維持動脈壓穩態值的恆定向來被視為循環系統的主要功能。然而近年來許多證據證明在正常生理範圍內，動脈壓的動態變異性(APV)對生命的維持也很重要。這些波動以頻譜分析能明確量化。經多年研究發現其中不同頻率波動有其特定的生理意義；再動脈壓心律以下的律動主要有三群分佈，可簡單分為與呼吸頻率一致之高頻(HF)及與血管運動有關之低頻(LF)及極低頻(VLF)成分。其中證明逼頻率成分的重要性證據有；在人的心臟到手術，心臟與血管沒連接時動脈壓訊號中仍存有低頻成分；重症病房病人動脈壓低頻消失達2天以上，有死亡的危險；大白鼠動物實驗中此低頻波動巴比妥鈉麻醉藥明顯壓抑，交感神經之α-adrenoceptor阻斷劑可明顯抑制此波動；高血壓大鼠低頻波動正常血壓鼠高。另外，探討動脈壓低頻成分來源的研究有；植物人仍存在低頻成份，但腦死病人則消失；寬頻電興奮延腦血管運動中樞(RVLM)可強烈引發低頻波動，且α1-adrenoceptor阻斷劑可抑制此作用；除了RVLM外，中樞許多神經核有類似調節動脈壓低頻波動作用，但物理特性有些不同；以低頻率電興份大鼠人中穴，可有效增加低頻波動； 高血壓大鼠RVLM動態控壓能力及反應速度皆較正常血壓鼠為高且快。以上證據顯示動脈低頻波動的來源可能為腦幹之血管運動中樞，且與自主神經之交感神經活性有關，其間α-adrenoceptor扮演主要角色。而高血壓大鼠之腦幹壓能力較強，可能為其高血壓的形成原因之ㄧ。(慈濟醫學2003; 15:1-12
並列摘要
Maintaining a static value of arterial pressure within a normal range is vital. On the hand evidence has demon-strated that proper arterial pressure variability(APV) is also important for normal health. Nowadays, power spectral analysis of arterial pressure for quantifying APV has gained in popularity. Using this tool inestigators has been able to evaluate various physiogical mechamisms underlying APV . They have found three major spectral components of APV below the frequency of the heart rate. The high-frequency component is sychronzed with respiratory rhythm,whereas the low-frequency (IF) and very low-frequency(VLF) components have been realted to vasomotor activities. During cardiopulmonary bypass, while the heart is disconnected from the blood vessels, the VLF component still persists.In critical care units, the sustained disappearance of LF/VLF components for more than 2 days is a warning sign of impending mortality, Animal studies have revealed that pentobarbital anesthesia significantly suppresses the LF/VLF components in the rat. Antagonism of the α-adrenoceptor also suppresses these components. LF/VLF compo-nents are strongly exaggerated in spontaneously hypertensive rats (SHR) as compared to normotensive rate. Exploring the origins of LF/VLF components is also promising. These components occur in vegetative patients but not in brain-dead patients. Broad-band electrical stimulation of the rostral ventrolatral medulla (RVLM)largely inducs LF/VLF components. These effects, however, are prevented by pretreatment with an α-adernoceptor antagonist. Apart ftom RVLM, many brain nuclei may also produce similar produce similar effects but with different physical characteristics. Frequency-modulated electroacupuncture on the Renzhong point significantly evoked LF/VLF components of APV. In addition, the dynamic regulation of pressure from the RVLM in SHR is more potent and faster than that in normotensive rats. The above evidence strongly suggests that the LF/VLF components of APV originate from the brain stem, and are related to sympathetic activity, in which the α-adrenoceptor may play a major role. Enhancement of bra1nstem vaso-mototr control in SHR may partly explain their etiology of hypertension.(Tau Chi Med J 2003; 15:1-12)