Acupuncture points (acupoints) form part of the meridian system that constitutes the most fundamental concept in oriental medicine, but their physiological basis has not been clarified. In this study we employed laser Doppler flowmetry (LDF) to extract the microcirculatory characteristics of acupoints and their surrounding tissues, and we interpreted the results from the viewpoint of microcirculatory physiology. Three groups of measurements were performed focusing on the following two important acupoints in oriental medicine in healthy volunteers (n = 13 for group A and n = 9 for groups B and C, respectively): Hoh-Ku (Li4, on the hand) and Ching-Ku (B64, on the foot). The two groups of measurements around Hoh-Ku (Groups A and B) were so designed as to examine the effect of the direction of the nonacupoint away from the acupoint, whereas comparison between the Hoh-Ku and the Ching-Ku measurements was to verify whether the phenomenon was consistent in the upper and the lower extremities. We found that the mean LDF signals were significantly larger at the acupoints than in their surrounding tissues (all p < 0.05), which indicates a larger blood supply into the microvascular beds of acupoints. The results indicate that the physical properties of the vascular structure of acupoints may affect the perfusion resistance, and thereby modulate the microcirculatory perfusion in accordance with tissue needs. This finding facilitates the localization of acupoints, helps in identifying the connection between microcirculatory physiology and responses to acupoint stimulation, and introduces an objective research method for understanding the mechanisms that underlie oriental medicine.

The present study used laser Doppler flowmetry (LDF) to investigate the connection between skin microcirculatory flow and the length of the RR interval (LRR). Local heating was performed on healthy volunteers to further elucidate its effect on LDF index. ECG and LDF signals were measured in 102 trials on seven volunteers. Each experiment involved a 5 min control and a 5 min heating-effect sequence. Each laser Doppler flux pulse was categorized into four groups according to its LRR compared with the 5 min average LRR. Synchronized averaging analysis was applied to the four groups of pulses to obtain their averaged waveforms, from which four flux parameters were calculated. The ac component of the flux increased significantly with increasing LRR, and the differences therein between the groups with LRR more than 4% smaller and more than 4% larger than the average LRR increased from 15.8% during the control period to 23.9% during the heating period. Understanding of the different flux responses between the control and local-heating experiments may aid the development of a new index, which helps to avoid LDF's main drawback of providing only qualitative measurement.

Based on the resonance theory, the pressure wave of the arterial system could reflect the physical condition of the internal organs. Experimental evidence indicates that the physical condition of organs is related to various Fourier components of the pressure pulse. We have proved that the first harmonic of the pressure-wave spectrum is closely related to the liver. In this study, Wistar rats given massive doses of acetaminophen were examined. The amplitude of the first harmonic of the blood pressure pulse, A1, was analyzed and correlated with the blood liver function indexes that examine serum glutamate pyruvate transaminase (SGPT) and serum glutamic oxaloacetic transaminase (SGOT). When A1 was below 3650 and SGPT was above 90, the kappa value was about 0.6; the probability is greater than. 999 based on a chi-square test. When A1 was below 3650 and SGOT was above 380, the kappa value was around 0.5; the probability is greater than. 999. Our results indicate that A1 may be used as a simple, real-time biomarker that is complementary to the commonly used first-line liver indicators, SGPT and SGOT levels, for monitoring acute hepatotoxicity. It promises a noninvasive, real-time liver-function monitoring method.

Our previous study revealed that the coefficient of variation of harmonic magnitude (HCV) of radial arterial pulse was significantly raised before the death of cancer patients. In this study, we recorded the caudate arterial pulse of 24 Sprague-Dawley rats that had a fatal dose of urethane injected into their abdomens. Twenty rats were dead within 3 hours after the injection and four survived. We defined the last 100 minutes of each rat's life as the dying process. During the dying process, we found that both the systolic blood pressure and diastolic blood pressure dropped steeply during the last 5 minutes. However, all HCVs, except HCV1, climbed steeply before the last 5 minutes. The HCV1 of the dying rats was significantly higher than that of rats that survived, starting from the first minute (P < 0.01). The HCV2 of the dying rats was significantly higher than that of the survived rats starting from the 52nd minute (P < 0.05). The HCV3 and HCV4 of the dying rats were significantly higher than those of the survived rats until the 70th minute and the 80th minute, respectively (P < 0.05). Furthermore, HCV2-HCV4 proceeded with the dying process and increased gradually. We concluded that HCVs, which failed first in the high-frequency components and then in the low-frequency components, could provide physicians with earlier information to prevent the coming failure of circulatory system, and could reflect quantitatively pathological severity and predict patient outcome. The specific Fourier components in the pulse provide more physiological information than systolic and diastolic blood pressures.

Meridian system composed of acupoints is the most fundamental concept to build oriental medicine. In this study, we employ LDF measurement to compare the microcirculatory blood velocity of acupuncture point and its surrounding tissues. Measurements were performed around an important acupoint in oriental medicine, Hoh-Ku (Li4, on the hand), in healthy volunteers. The study presented has shown that the acupoints have significantly slower mean blood velocity than their surrounding tissues (p all < 0.005). This finding facilitates the detection of the position of acupuncture point and helps us to provide a possible connection between microcirculatory physiology and the underlying mechanism of acupoints.