A study of electrical stimulation of acupuncture locus tsusanli (St-36) on mesenteric microcirculation

Acupuncture in Modern Medicine

Acupuncture, developed thousands of years ago in the Orient, is increasingly being integrated into modern Western Medicine. Its neurophysiological basis is partly understood, and controlled trials are demonstrating its efficacy and safety.

Electroacupuncture analgesia in dogs: is there a difference between uni- and bi-lateral stimulation?

OBJECTIVE

To compare the analgesic effect of uni- and bi-lateral electroacupuncture (EA) in response to thermal and mechanical nociceptive stimuli and to investigate the cardiorespiratory, endocrine, and behavioral changes in dogs submitted to EA.

STUDY DESIGN

Prospective, randomized cross-over experimental study.

ANIMALS

Eight adult, clinically healthy, cross-breed dogs, weighing 13 +/- 4 kg.

METHODS

Dogs underwent electrostimulation at false acupoints (T-false); bilateral EA at acupoints, stomach 36, gall bladder 34 and spleen 6 (T-EA/bil); unilateral EA at the same points (T-EA/uni) or were untreated (T-control). All animals received acepromazine (0.05 mg kg(-1)) IV; and heart rate, pulse oximetry, indirect arterial blood pressure, respiratory rate, Pe'CO(2), rectal temperature, and plasma cortisol concentration were measured before, during, and after EA. Analgesia was tested using thoracic and abdominal cutaneous thermal and mechanical stimuli, and an interdigital thermal stimulus. Behavior was classified as calm or restless. Analysis of variance for repeated measures followed by Tukey's test was used for analysis of the data.

RESULTS

There were no cardiorespiratory differences among the treatments. The cutaneous pain threshold was higher after EA, compared with false points. The latency period was shorter and analgesia was more intense in T-EA/bil than T-EA/uni, when both were compared with T-false and T-control. Six out of eight animals treated with EA were calm during treatment, and 5/8 and 4/8 of the T-false and T-control animals, respectively, were restless. Latency to interdigital thermal stimulation increased in T-EA/bil compared with the others. There was no difference in plasma cortisol concentrations among the treatments.

CONCLUSIONS

Bilateral EA produced a shorter latency period, a greater intensity, and longer duration of analgesia than unilateral stimulation, without stimulating a stress response.

CLINICAL RELEVANCE

Bilateral EA produces a better analgesic effect than unilateral EA.

Effects of Electroacupuncture Stimulation Applied to Limb and Back on Mesenteric Microvascular Hemodynamics

The effects of electroacupuncture stimulation (EAS) of the hind paw and the back on the mesenteric microhemodynamics in anesthetized rats were investigated using an intravital microscope system. Red blood cell (RBC) velocity in the mesenteric arterioles was measured by the dual-sensor method developed by the authors. Electrical stimulation was applied using two acupuncture needles inserted into the skin and the underlying muscles of the hind paw and the dorsal Th13-L1 level area. The hind-paw EAS evoked intensity-dependent pressor responses and increase responses in RBC velocity in mesenteric precapillary arterioles, while the back EAS evoked depressor responses and decrease responses in RBC velocity. Heart rate showed increase responses accompanying EAS either on the hind paw or the back. The pressor responses and increase responses in RBC velocity in mesenteric precapillary arterioles accompanying the hind paw EAS were abolished by an intravenous administration of alpha-adrenergic receptor antagonist (phenoxybenzamine; POB), and the tachycardiac responses were abolished by administration of beta-adrenergic receptor antagonist (propranolol). Occasional but notable reflex vasoconstrictions in the mesenteric terminal arteriole were induced by EAS either on the hind paw or the back. These vasoconstrictive responses were not affected by the administration of POB. The present study directly demonstrated that hemodynamic changes at the level of precapillary arterioles accompanying EAS either on the hind paw or the back mainly depend on the changes of systemic arterial pressure regardless of stimulus current intensities. Moreover, the results in the present study suggest some receptors other than alpha-adrenergic receptor might be involved in the mechanism of EAS-induced vasoconstriction in the mesenteric arteriole.

Comparison of electroacupuncture and butorphanol on respiratory and cardiovascular effects and rectal pain threshold after controlled rectal distention in mares

OBJECTIVE

To compare effects of electroacupuncture and butorphanol on hemodynamic and respiratory variables and rectal analgesia in mares after controlled rectal distention.

ANIMALS

8 healthy mares.

PROCEDURE

Each horse received saline (0.9% NaCl) solution (0.01 mL/kg, IV; control treatment), butorphanol tartrate (0.1 mg/kg, IV), or 2 hours of electroacupuncture (EA) at acupoints Bladder 21, 25, and 27 on both sides of the vertebral column, Bai hui, and Stomach 36 (right side only). Order of treatments in each mare was randomized. At least 7 days elapsed between treatments. A balloon was inserted in the rectum of each mare, and controlled distention of the balloon (pressures of < or = 220 mm Hg) was used to measure nociceptive rectal pain threshold. Rectal temperature and cardiovascular and respiratory variables were measured before (baseline) and 5,15, 30, 60, 90, and 120 minutes after onset of each treatment.

RESULTS

Butorphanol produced greater increases in rectal pain threshold, compared with EA (mean +/- SD, 214 +/- 24 vs 174 +/- 35 mm Hg of balloon pressure). Electroacupuncture produced minimal cardiovascular and respiratory changes. Although clinically not important, butorphanol produced moderate significant increases in heart and respiratory rates, arterial blood pressure, and rectal temperature and decreases in arterial oxygen tension. Arterial pH, carbon dioxide tension, bicarbonate concentrations, base excess, Hct, and concentration of total solids were not significantly different from baseline values after EA, butorphanol, and control treatments.

CONCLUSIONS AND CLINICAL RELEVANCE

Electroacupuncture and butorphanol (0.1 mg/kg, IV) may provide useful rectal analgesia in horses.

Somatosensory nociceptive mechanical stimulation modulates systemic and mesenteric microvascular hemodynamics in anesthetized rats

The effects of somatosensory nociceptive pinch stimulation of the hindpaw on mesenteric microvascular hemodynamics and systemic circulatory parameters were investigated in anesthetized rats using an intravital microscope-television system. Blood flow velocity in the terminal (18-40 microm in diameter) or precapillary (10-20 microm in diameter) arterioles of the mesentery was monitored by the dual sensor method developed by the authors. In the proximal terminal arterioles, blood flow velocity decreased substantially along with arteriolar constriction induced by pinching of the hindpaw for 30 s. In the distal terminal arterioles and precapillary arterioles, blood flow velocity increased after pinching. In the proximal terminal arterioles, the decrease of velocity in response to reflex vasoconstriction was abolished by intravenous injection of an alpha-blocker (phentolamine, 10 mg/kg). The increase in mesenteric precapillary arteriolar blood flow velocity (43+/-9%, p < 0.01) associated with the increase in mean arterial pressure (MAP) (22+/-1%, p < 0.01) was observed within a few seconds after the onset of the stimulation, and then the response in blood flow velocity returned to the baseline ahead of MAP response recovery after the end of the stimulus. These responses were diminished by alpha-adrenergic receptor blockade. The heart rate (HR) increase (4+/-1%, p < 0.01) induced by pinching was abolished by beta-adrenergicreceptor blockade (propranolol, 3 mg/kg, i.v.). There was a strong correlation between the increase in MAP and the decrease in renal blood flow measured by laser Doppler flowmeter (r = 0.87-0.98). Pinch stimulation of the rat hindpaw evoked changes in mesenteric arteriolar blood flow velocity that were mediated via the somato-sympathetic reflex vasoconstriction and the pressor response.

Results of transcutaneous electrical stimulation (TES) in cure of lower extremity arterial disease

The results of the treatment of 24 subjects--10 of them diabetic--with peripheral obstructive arterial disease of the lower limbs by transcutaneous electrical stimulation (TES) have been studied. The chronic ischemia of the lower extremities was complicated with ulceration in 12 and initial or advanced gangrene in 6 patients. All patients had been treated with antiplatelet drugs, pentoxifylline, and vasodilating drugs for many years. The drug therapy was continued, and TES was given daily for twenty minutes. The results were estimated after four to eight weeks of hospitalization and during a one-year follow-up in numerous cases. Except for 4 patients the improvement was very significant in all cases: the pain disappeared, the gangrenous process of the toes stopped, regression or complete healing of the ulceration could be observed, and the painfree walking distance increased. The oxygen saturation measured on the toes increased significantly during electrical stimulation. The blood pressure measured in the tibial artery showed very different changes. According to these observations TES appears to be a useful method superior to drug therapy in curing arterial circulatory disturbances of the lower extremities.

Sympathetic effects of manual and electrical acupuncture of the Tsusanli knee point: comparison with the Hoku hand point sympathetic effects

Sympathetic effects of manual and electrical acupuncture of the Tsusanli knee point were evaluated by thermography in 19 normal subjects under the same procedure used in a previous study using the Hoku hand point. A generalized long-lasting warming (sympathetic inhibition) effect was observed under manual and electrical acupuncture of the Tsusanli point. In addition, a segmentally related short-lasting cooling (sympathetic activation) effect occurred with Tsusanli electrical acupuncture only. The warming effect is consistent with the results of the Hoku study and appears to be a central sympathetic inhibition evoked by acupuncture. The cooling effect was segmentally related to the acupuncture site in both studies. This cooling effect most likely reflects a segmental activation of vasomotor spinal reflexes and not a general emotional arousal. These sympathetic mechanisms may be functionally correlated with central and peripheral mechanisms of acupuncture analgesia.

Use of transcutaneous nerve stimulation in the attacks of acute intermittent porphyria

A 38-year-old female with acute intermittent porphyria (AIP) was having regular recurrent premenstrual severe attacks of abdominal and chest pain due to the disease. Low-frequency transcutaneous nerve stimulation (TNS) premenstrually prevented or markedly reduced the severity of clinical attacks, associated with a reduced urinary porphyrin excretion. The possible mechanisms of the TNS-induced effects are discussed. This experience suggests that TNS may be an effective and simple prophylactic method in the management of the attacks in AIP. The method can be administered easily by the patient himself as home-treatment and is free of side-effects.

Sympathetic vasomotor changes induced by manual and electrical acupuncture of the Hoku point visualized by thermography

Considerable evidence implicates sympathetic neural activity in acupuncture analgesia. However, the exact nature of these effects has not been specified in detail, and many experimental findings are contradictory. This study evaluated in normal conditions the specific sympathetic effects of both manual and electrical acupuncture applied to the same hand (Hoku) point. Thermographic measures of superficial skin temperature were used to assess sympathetic vasomotor tone in the face, hand and foot of 19 normal subjects. Baseline assessment, manual acupuncture and electrical acupuncture were performed in 3 separate sessions in a well controlled, 23 degrees C environment. Superficial skin temperature decreased slowly in the control condition. Both manual and electrical acupuncture produced a generalized long-lasting warming effect, indicating reduced sympathetic activity (sympatholytic effect). In addition, electrical acupuncture induced a localized short-term cooling effect, indicating a transient segmental increase in sympathetic activity (sympathomimetic effect).

In search of mediators of skin vasodilation induced by transcutaneous nerve stimulation: III. Increase in plasma VIP in normal subjects and in Raynaud's disease

Previous studies have shown that the widespread and sustained cutaneous vasodilation which can be induced by low-frequency transcutaneous nerve stimulation (TNS) in humans is dependent on a central serotonergic pathway leading to peripheral sympatho-inhibition. In addition, in a bioassay study, the release of a peripheral vasodilator was suggested. However, the TNS-induced dilator response was not blocked by antagonists to a series of known endogenous vasodilators. In the present study another candidate, the vasoactive intestinal polypeptide (VIP) was monitored by means of a specific radioimmunoassay. The results showed an increase in plasma VIP from 5.6 pmol X l-1 before TNS to 7.3 pmol X l-1 after TNS (median values for 15 normal volunteers; P less than 0.05 for the 30% increase). Patients with Raynaud's disease displayed lower levels of VIP than the normal group (median 3.7 pmol X l-1 for 20 patients; P less than 0.01 for the difference from normals). TNS-induced rewarming of the extremities in Raynaud patients was paralleled by 35% increase in plasma VIP (median 5.0 pmol X l-1; P less than 0.01 for the TNS-dependent increase). The results suggest that the TNS-induced increase in plasma VIP parallels the increase in skin temperature in the extremities. However, a causal relationship between the increase in plasma VIP and cutaneous vasodilation remains to be determined. Possible origins of the TNS-dependent increase in plasma VIP are discussed.

Failure to influence the VIP level in the cerebrospinal fluid by transcutaneous nerve stimulation in humans

Low-frequency transcutaneous nerve stimulation (TNS) is known to produce a prolonged and widespread cutaneous vasodilatation. This is associated with a moderate but significant increase of 30-35% in the concentration of the vasoactive intestinal polypeptide (VIP) in the cubital vein plasma. A possible source of this increased plasma VIP following TNS is the central nervous system. This possibility is tested in the present experiment. The concentration of VIP in the cerebrospinal fluid (CSF) was determined by radioimmunoassay in 9 patients with no organic disease of the central nervous system, before and at various intervals (15, 30 and 45 min) after the onset of TNS. No significant change in the VIP level of the cerebrospinal fluid was encountered, although the stimulation evoked rises in finger temperature indicating effectiveness of the stimulation. It is concluded that the stimulation-induced increase in plasma VIP is due to release of VIP outside the brain.