Acupuncture’s Cardiovascular Actions – A Mechanistic Perspective

1. Overview · 概述

Over the last few decades, basic and clinical studies have begun to clarify how acupuncture influences cardiovascular function. Longhurst’s work focuses on how stimulation of specific acupoints, especially with low-frequency electroacupuncture (EA), can modulate blood pressure and sympathetic outflow through defined neural pathways.

過去數十年，基礎與臨床研究逐漸釐清針灸如何影響心血管功能。Longhurst 的研究特別聚焦在：以低頻電針刺激特定穴位時，如何透過明確的神經迴路，調節血壓與交感神經輸出。

2. Point Specificity: Which Acupoints Really Work? 穴位特異性：哪些穴位真的對血壓有影響？

An important question in Traditional Chinese Medicine is whether different acupoints have “point-specific” effects. Some clinical trials support this concept, while others do not, partly because of weak study designs and inadequate sham controls. From a neurobiological perspective, however, it is unlikely that all body sites have identical effects, because somatic nerves are distributed unevenly and project to different central pathways.

在中醫理論中，「穴位特異性」是重要概念：不同穴位是否真的對不同疾病具有特定效果？臨床試驗的系統性回顧顯示，有些研究支持，有些則不支持，主要和研究設計、假針控制不嚴謹有關。但從神經生理的角度來看，身體各部位的神經分布並不平均，也不可能都投射到同一個中樞，因此不太可能「針哪裡都一樣」。

Overall, Longhurst’s work supports the existence of point specificity from a neural standpoint: acupoints located over deep somatic nerves are much more effective for reducing elevated blood pressure than those lying only over superficial cutaneous nerves.
總結來說，Longhurst 的研究從神經生理角度支持「穴位特異性」：位於深層體神經的穴位，在降壓與調節交感神經方面，明顯優於僅位於表層皮神經的穴位。

3. Electroacupuncture (EA): How Is It Applied? 電針是如何應用的？

In Longhurst’s cardiovascular studies, electroacupuncture (EA) is the primary stimulation method because it provides a stable and reproducible stimulus. Needles are inserted into the muscle layer at specific acupoints, and a low-frequency current is applied.

在心血管相關的實驗中，Longhurst 主要使用電針作為刺激方式，因為它可以提供穩定且可重複的刺激。針刺入肌層之後，以低頻電流刺激特定穴位。

In preliminary clinical studies on mild-to-moderate hypertension, this protocol reduced systolic blood pressure by about 8–12 mmHg in approximately 70% of patients, with a slower onset (after 2–4 weeks) and prolonged effects lasting several weeks after an 8-week course.
在輕至中度高血壓患者的初步臨床研究中，上述電針方案可使約 70% 的患者收縮壓下降約 8–12 mmHg，起效較慢（約自治療 2–4 週後開始），且在連續 8 週療程結束後，降壓效果仍可持續數週。

4. Why Does Acupuncture Have a Prolonged Effect? 為什麼針灸的效果可以維持那麼久？

Experimental studies show that 30 minutes of EA can reduce elevated blood pressure for 1–1.5 hours beyond the stimulation period in anesthetized animals. This prolonged action involves a long-loop pathway linking the hypothalamic arcuate nucleus, the midbrain ventrolateral periaqueductal gray (vlPAG), and the medullary rostral ventrolateral medulla (rVLM). Within this loop, reciprocal excitatory connections reinforce and extend the cardiovascular response.

實驗研究顯示，在麻醉動物中，單次 30 分鐘的電針，對升高的血圧可產生額外 1–1.5 小時的持續降壓作用。這種延長效果與一條「長迴路」有關：下視丘弓狀核、中腦水管周圍灰質（vlPAG）與延腦 rVLM 之間存在互相增強的連結，強化並延長心血管反應。

Opioids and GABA in the rVLM also participate in this prolonged response. Beyond acute neurotransmitter release, repeated EA over days or weeks upregulates preproenkephalin mRNA and enkephalin protein expression, leading to much longer-lasting modulation of blood pressure that can persist for hours or days after treatment.

rVLM 區內的阿片肽與 GABA 也參與這種持續反應。除了急性神經傳遞物質釋放之外，連續幾天或數週的重複電針，會上調 preproenkephalin mRNA（腦啡前驅基因）及腦啡蛋白的表現，使降壓調節的作用可持續數小時甚至數天。 Longhurst 因此推測：在初期療程有效降壓之後，只要每月維持 1–2 次治療，可能便足以穩定血壓。

5. Why Are Some Patients Nonresponders? 為什麼有些人對針灸沒有反應？

Clinical and experimental data suggest that about 70% of individuals respond to acupuncture, leaving roughly 30% as nonresponders. One proposed mechanism involves cholecystokinin (CCK), particularly CCK-8, which is widely distributed in the brain and exerts anti-opioid actions.

臨床與實驗研究皆指出，大約有 70% 的個體對針灸有明顯反應，約 30% 屬於「無反應者」。其中一個可能機轉與膽囊收縮素（CCK）有關，尤其是廣泛分布於腦內的 CCK-8，其具有「抗阿片」作用。

In animal studies, CCK-8 in the rVLM, acting through CCK-A receptors, appears to block the antihypertensive effects of EA. Preliminary experiments show that administering a CCK-8 antagonist can convert EA nonresponders into responders, suggesting that CCK tone may determine individual sensitivity to acupuncture.

動物實驗顯示，在 rVLM 區域內，CCK-8 透過 CCK-A 型受體，會抵消電針的降壓作用。初步研究亦發現，若給予 CCK-8 拮抗劑，原本對電針沒有反應的個體，可能變成「有反應者」。這提示 CCK 系統的活性，可能是決定個體對針灸敏感度的重要因素之一。

6. From Experimental Models to Clinical Practice 從實驗模型走向臨床應用

A key question is whether insights from anesthetized animal models translate to human clinical acupuncture. Longhurst’s answer is “probably yes.” In humans, EA does not lower blood pressure when it is normal but can attenuate exercise-related pressor responses. In patients with mild-to-moderate hypertension, EA at experimentally validated acupoints (PC 5, PC 6, ST 36, ST 37) using the effective stimulus paradigm has shown promising reductions in blood pressure.

一個關鍵問題是：在麻醉動物身上得到的機轉，是否能轉化為人體臨床的針灸治療？Longhurst 的回答是「很可能可以」。在人類研究中，電針不會降低正常血壓，但可減少運動引起的升壓反應；而在輕中度高血壓患者中，使用實驗上證實最有效的穴位組合（PC 5、PC 6、ST 36、ST 37）與刺激模式，也已觀察到具有臨床意義的降壓效果。

To confirm that these effects are not purely placebo, future trials must compare active EA at cardiovascularly effective acupoints with strong sham controls, such as stimulation at inactive acupoints or needle insertion without sustained stimulation.
為了確認這些效果並非單純安慰劑，未來臨床試驗需要嚴格的對照設計，例如：和「心血管上無效穴位」的治療相比，或與僅插針而不持續刺激的控制組相比，以更清楚區分真實生理作用與心理效應。

7. Clinical Implications and Conclusions 臨床啟發與總結

Acupuncture’s cardiovascular actions can now be understood largely in terms of peripheral and central neural mechanisms. Stimulation of specific deep-nerve acupoints activates somatic afferents that project through the spinal cord to hypothalamic, midbrain, and medullary centers. Through the release of excitatory and inhibitory neurotransmitters, these pathways modulate autonomic outflow and thereby alter blood pressure and cardiac load.

目前，我們已能相當清楚地以周邊與中樞神經機轉來理解針灸的心血管作用。刺激特定、位於深層神經上的穴位，會活化體感傳入纖維，經脊髓上行至下視丘、中腦與延腦等中樞區域；這些區域再透過多種興奮性與抑制性神經傳導物質，調節自主神經輸出，進而影響血壓與心臟負荷。

While much has been learned, many questions remain about optimal clinical protocols, individual variability, and long-term outcomes. Nonetheless, Longhurst’s work provides an important mechanistic foundation to support the integration of acupuncture into the management of conditions such as hypertension, myocardial ischemia, and autonomic imbalance.
雖然我們已累積了大量機制層面的資料，但在最適臨床方案、個體差異與長期預後等方面，仍有許多問題尚待釐清。儘管如此，Longhurst 的研究已為針灸介入高血壓、心肌缺血與自主神經失調等疾病，提供了重要且具說服力的神經生理基礎。

Reference · 參考文獻

Longhurst JC. Acupuncture’s Cardiovascular Actions: A Mechanistic Perspective. Medical Acupuncture. 2013;25(2):101–113. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC3616410/