Acupuncture has a long history of use to treat many conditions, including pain, depression, fatigue and addictions. It is known to effect local responses as well as distal changes through neurological and endocrine systems. When used together with heat treatment it can cause multiple biological responses, seen both in animals and humans. However, the mechanism and biochemical changes responsible for these effects are still unclear. Chinese concepts refer to the flow of Qi, five element theory and yin and yang. Anatomical studies show that most acupoints located along the meridian lines (also known as channels) are located closely to nerve fibre distribution and blood vessels. Interestingly, there is also an increase in hair follicles and sweat glands at these points.
Nitrous Oxide (NO) is known to play an important physiological role in skin local microcirculation, neurotransmission, immunity and wound healing. It produces relaxation of blood vessels via an increase in NO synthase acitivty, but also utilizes the nitrate-nitrite-NO pathway in the human skin. Studies in rats have also shown that NO content and NO synthase protein levels are in the skin tissue at acupoints and meridian lines. Repeated thermal application also increases immunoreactivity and NO synthase in hamsters. NO also mediates noradrenergic function on skin sympathetic nerve activation, which contributes to low resistance characteristics of acupoints and meridians.
One crossover study conducted on 20 volunteers who underwent a real acupuncture and then non-invasive sham acupuncture in the hand or forearm with 1 week interval between treatments. The blood plasma concentration of NO in the acupunctured arm and hand was significantly increased, which was not observed in the sham acupuncture.
A more recent published study at the Harbor-UCLA Medical Center examined the effect of manual acupuncture and electrical heat to the release of nitric oxide (NO) over the human skin. Participants included 25 volunteers (men and women) aged 18-60 yrs. Participants were randomly asked to undergo manual acupuncture over the pericardium meridian, or heat treatment over the lung meridian. NO was monitored using a Biocapture device with a collecting solution taped to the skin along the meridians. Results found that manual acupuncture and electrical heat cause release of NO from the local skin, which was almost doubled at acupuncture points.
Initial pilot studies also show that the extent of NO production can vary depending on the person’s age and gender due to the differences in sympathetic acitivity, body weight, hormones, sweat rates and skin thickness. There was no noticeable difference between different ethnic groups.
The importance of a rich blood circulation is an evident necessary part of tissue healing, and suggests the rationale for subsequent pain relief or sensitising substances. These studies determined that acupuncture elevates the local level of NO in the treated areas, thus increasing blood flow and warmth. There is vasodilation accompanied neurochemical changes which may further contribute to generation of NO. Thus suggesting that acupuncture treatment using a reinforced technique and the addition of electrical heat will improve local circulation.
Clinical experience has shown that the use of acupuncture for pain relief is an excellent alternative to the use of medicinal pain killers. However we must not ignore the benefits of increase blood circulation for other conditions, therefore improving the overall body functions. My own clinical practice regularly incorporates the use heat in the form of direct or indirect moxa or electrical heat. We have always found that the addition of heat enhances the needle effects, thus confirming the above research findings. It should be a treatment choice for those experiencing pain but in particular where there is chronic pain.