Involvement of the mechanoreceptors in the sensory mechanisms of manual and electrical acupuncture

The modalities of acupuncture can be broadly classified into manual acupuncture (MA) and electroacupuncture (EA). Although MA has been reported to cause winding of tissue around the needle and subsequent activation of the sensory mechanoreceptors and nociceptors, the sensory mechanisms of acupuncture stimulation are not fully understood. To test the hypothesis that the involvement of the mechanoreceptors in the sensory mechanism is different in MA and EA, we examined the effects of a stretch-activated channel blocker gadolinium on the hemodynamic responses to hind limb MA and EA in anesthetized rats (n = 9). Gadolinium significantly attenuated the MA-induced bradycardic response (-22 ± 5 vs. -10 ± 3 bpm, P<0.05) and tended to attenuate the MA-induced depressor response (-30 ± 5 vs. -18 ± 4 mmHg, P = 0.06). On the other hand, gadolinium significantly attenuated both the EA-induced bradycardic (-22 ± 5 vs. -9 ± 4 bpm, P<0.01) and depressor responses (-32 ± 6 vs. -15 ± 5 mmHg, P<0.01). These results indicate that the mechanoreceptors are involved in the sensory mechanisms for both MA and EA.     

The effects of ipsilateral forearm movement and contralateral hand grasp on the spastic hand opened by electrical stimulation

The purpose of this study was to investigate the effects of ipsilateral arm movement and contralateral hand grasp on the spastic hand opened by open-loop electrical stimulation. The major problem of applying proper electrical stimulation is variable spasticity, the intensity of which changes with posture and movements of other parts of the body. Electrical stimulation was applied to extensor digitorum communis and ulnar nerve to open the affected hand. Different procedures were then used to assess the effects of moving the ipsilateral forearm and contracting the contralateral normal hand. Electrical stimulation opened the spastic hand in more than 95% of trials in all subjects, whether stimulation was applied before or after the movement of the forearm. Moving the ipsilateral forearm did have an effect on opening the hand, and making adjustment of stimulation intensities was necessary in all subjects. The stimulation opened the spastic hand during the contraction of the contralateral normal hand. Electrical stimulation could open the spastic hands most of the time, in the presence of ipsilateral forearm movement and contralateral normal hand contraction. If electrical stimulation was applied before the ipsilateral forearm was moved toward the target, stimulation intensities needed to be adjusted.     

Sympathetic skin responses: the influence of electrical stimulus intensity and habituation on the waveform

Abstract Repeated stimulation of the sympathetic skin response (SSR) causes habituation. The aim of this study was to determine the effects of electrical stimulus intensity on SSR in 40 healthy controls (mean age±SD, 28.0±6.7 years). Electrical stimuli at three intensities (5, 15 and 30 mA) were applied to the median nerve at the wrist in four consecutive sessions, after which a magnetic stimulus was applied to the neck. SSR were classified according to the proportion of positive (P) and negative (N) waveform components.Twentyfour subjects had both P and N waveforms. In the first session, 75% of these subjects had a P waveform, indicative of a greater SSR, in response to the 30 mA shock. In the progressive sessions, the SSR waveform was predominately negative (N waveform, session 2, 65%; session 3, 83%; session 4, 75% in response to 30 mA shock), indicating that the SSR was weaker as a result of habituation. There was no clear relationship between stimulus intensity and waveform type, indicating that SSR waveforms are more strongly influenced by habituation than stimulus intensity. However, there was a directly proportional relationship between stimulus intensity and amplitude of the SSR wave (F=70.9, P<0.0001, two-way repeated measure ANOVA), be it positive or negative. The relationship between stimulus intensity and amplitude persisted, even after habituation. Suddenly switching to a magnetic stimulus reverted the SSR wave back to positive (80%), indicating that habituation was rapidly reversible if stimulation of the SSR is altered.     

Sympathetic control of antral and pyloric electrical activity in the rabbit

The effects of section and stimulation of the sympathetic nerve trunk on gastric motility were investigated in conscious and decorticate rabbits. In conscious animals after section of the abdominal splanchnic nerve, rhythm of antral and pyloric bursts was enhanced, becoming more regular, and the period of arrest of the rhythmic bursts, which was usually observed at the end of inflation of the antrum in intact rabbits, was shortened to 33.6 +/- 4.0 s from 112.2 +/- 14.6 s observed before the sympathetic nerve transection. Adrenergic agonists, phenylephrine (100 micrograms/kg), clonidine (5 micrograms/kg) and salbutamol (1 mg/kg) inhibited antral and pyloric activity. In decorticate rabbits the major effect of stimulation of the peripheral or the central end of the thoracic sympathetic trunk was inhibition; this was seen both with the spontaneous and vagally induced e.m.g. activity of the antrum and pylorus. Inhibition induced by stimulation of sympathetic efferents was abolished by beta-blocking agents and that induced by stimulation of the sympathetic afferents disappeared after alpha-adrenergic block. Significance of a dual control of the gastric motility by the sympathetic nerve was discussed.     

Sympathetic skin responses of the hand in normal subjects: shorter latency at distal phalanx

We studied the conduction of the sympathetic skin response (SSR) in the hands of 35 normal subjects by simultaneous recording at five sites. The mean latency of the SSR in all subjects increased from the wrist (W) to the middle phalanx (M), but the SSR latency at the distal phalanx (D) was shorter than that at the middle phalanx. The mean conduction time and conduction velocity from W to M was 197.5 ms and 0.87 m/s, respectively, and that from W to D was 48.8 ms and 2.34 m/s, respectively. For evaluation of the cause of the shorter latency at D, digital nerve blocking was performed in two subjects. The blocking of the volar digital nerves at the proximal phalanx abolished SSR at M and D. It was postulated that the initiation or conduction of sudomotor nerve impulse to the distal phalanx would be facilitated compared with those to the other proximal sites in the hand. The SSR conduction time between W and M may be a means of detecting alteration of sympathetic sudomotor nerve activity.     

Intention tremor during manual aiming: a study of eye and hand movements

Accurate goal-directed movements toward a visual target require a precise coordination of both the oculomotor and limb motor systems. Intention tremor and eye movement deficits are frequently observed in multiple sclerosis (MS). The goal of this study was to examine the characteristics of intention tremor and simultaneously produced eye movements during rapid goal-directed movements. Eye and hand movements were synchronously measured in 16 MS patients with intention tremor and 16 control subjects. Manual performances of the patient group were characterized by a delayed onset, slower execution and aiming inaccuracies. In line with the clinically defined picture of intention tremor differences between patients and control subjects were most pronounced toward the end of the movement. Dependent variables were obviously greater in MS patients compared with control subjects, and correlated well with clinical outcome measures. The application of an inertial load to the limb did not show any effect on intention tremor. In addition to impaired limb coordination, evidence has been found that eye movements, too, were abnormal in patients compared with control subjects. Moreover, eye and hand movement deficits seemed to be closely related, suggesting a common underlying command structure. Inaccurate eye movements were likely to hamper an accurate motor performance of the hand.     

Sympathetic skin responses of the face and neck evoked by electrical stimulation

The sympathetic skin responses (SSRs) were recorded from different facial regions and neck in 25 subjects evoked by electrical stimulation of the median nerve at the wrist. Recordings from all regions were cross-compared with each other and within right and left sides individually. In one subject postauricular SSR, and in another subject upper lip SSR could not be elicited on both sides. Other responses could be obtained in all the remaining subjects. In 11 subjects, the responses did not appear by the first stimulus, and began to appear by repeated stimuli. Mean latencies and the highest amplitudes of the responses were similar for both sides. Gradual amplitude increase was observed in the first three or four set of responses in 20 subjects, although the stimulus intensity was constant. In conclusion, face and neck SSRs are symmetric, can be evoked by electrical stimulation and can be used to investigate the sympathetic innervation of these areas.     

Stimulation of gastric slow waves with manual acupuncture at acupuncture points ST36 and PC6--a randomized single blind controlled trial

Background To investigate the effects of stimulated and non‐stimulated manual acupuncture at ST36 and PC6 on gastric myoelectrical activity and autonomic function. Methods A total of 65 healthy volunteers were randomly assigned to a 1: 1: 2 ratio to receive either 15 min of verum acupuncture (VA) with stimulation followed by 15 min of VA without stimulation (nsVA), or 15 min of nsVA followed by 15 min of VA with stimulation (sVA), or 30 min of sham acupuncture (SA). Measures of autonomic function included electrogastrogram, electrocardiogram, impedance cardiography and assessment of blood pressure, breathing frequency, and electrodermal activity. Outcome parameters were compared between VA and SA, and between sVA and nsVA. The percentage of regular gastric slow waves (normogastria) was defined as the primary outcome. Key Results The percentage of normogastria was not significantly different between VA and SA. Differences in secondary outcomes such as power spectrum of gastric slow waves and heart rate variability parameters were pronounced in the comparison of sVA and nsVA. During sVA, the percentage of normogastria was lower (P = 0.005), the percentage of bradygastria was higher (P = 0.003) and power ratio was higher (P < 0.001), systolic blood pressure was lower (P = 0.039) and RMSSD was higher (P < 0.001) as compared with nsVA. Conclusions & Inferences Our study suggests that manual stimulation of acupuncture needles at ST36 and PC6 affects gastric myoelectrical as well as cardiac activities in healthy volunteers. The effect of stimulation in acupuncture deserves further investigation.     

Sympathetic activity in the rat: effects of anaesthesia on noradrenaline kinetics

Noradrenaline (NA) kinetics represent an effective tool for evaluating the activity of the sympathetic system: thus plasma NA concentration, spillover rate (SOR) and metabolic clearance rate (MC) were measured in the rat. The dilution technique was adapted and validated: pithing that caused mechanical destruction of the spinal cord was shown to reduce drastically NA-SOR and plasma NA concentration with no effect on NA-MC. NA-SOR and plasma NA concentration were restored within their normal limits when 2.5 Hz electrical stimulation of the sympathetic roots was superimposed. Normal values of NA kinetics in non-anaesthetised normotensive 12-week-old rats are reported: NA-SOR=196.1+/-26.4 ng/kg/min, NA-MC=413.9+/-38.8 ml/kg/min and plasma NA=486+/-52 pg/ml. NA kinetic was investigated in response to anaesthesia, known to depress excitable tissues of the central nervous system and expected to depress the activity of the sympathetic system. When NA-SOR was significantly reduced during anaesthesia with either sodium pentobarbital or chloralose, plasma NA concentration was not changed because NA-MC was also reduced. Thus, plasma NA concentration can be a misleading marker of the sympathetic activity. The response of the sympathetic activity to four different anaesthetic agents is shown to be heterogeneous, ranging from inhibition to stimulation. Sodium pentobarbital anaesthesia was associated with a statistically significant reduction of both NA-SOR (105.6+/-14.1 ng/kg/min, P<0. 01) and NA-MC (239.3+/-18.7 ml/kg/min, P<0.001) while plasma NA was not changed (438+/-47 pg/ml). Chloralose reduced NA-SOR (101.6+/-20. 1 ng/kg/min, P<0.05) while ketamine did not (150.6+/-35.5 ng/kg/min, n.s.): both compounds reduced NA-MC (257.9+/-27.8 ml/kg/min, P<0.01 and 265.8+/-34.3 ml/kg/min, P<0.05, respectively). Diethyl ether was shown to increase both NA-SOR (472.2+/-111 ng/kg/min, P<0.05) and plasma NA concentration (1589+/-436 pg/ml, P<0.01), while NA-MC remained unchanged. Thus, any investigation of the activity of the sympathetic system in the anaesthetised rat has to take into account the specific effects related to the anaesthetic agent used.     

Perclose缝合器与Boomerang血管封阻器对股动脉穿刺点的止血效应：与人工压迫法比较★

目的：观察冠状动脉造影术及支架置入术后应用两种血管穿刺闭合器在股动脉径路止血中的安全性和有效性，其结果与人工压迫止血方法对照。 方法：①实验对象：选择2006-03/2007-08在解放军空军总医院心内科住院的临床疑诊冠心病或确诊冠心病行冠状动脉造影或冠状动脉介入治疗的患者436例，男246例，女 190例，年龄44~75岁，平均（62.4±12.5）岁。所有患者对治疗和实验均知情同意。分为人工压迫止血组160例，Boomerang封堵器组140例，Perclose缝合器组136例。②实验仪器：Boomerang血管封堵器由美国Cardiva公司生产(产品批号: 610070521A, 型号: B610)，Perclose缝合装置由美国Abott公司生产(产品批号: 54145-6H, 型号: 12673)。③实验方法：a：压迫止血法：冠状动脉造影后立即拔除鞘管，局部压迫止血；经皮冠状动脉介入术患者术后送回病房，4 h后测活化部分凝血活酶时间达65 s以下时拔除鞘管，局部压迫止血。b：Boomerang封堵器法：严格按操作规范置入血管封堵器，在血管内留置时间依术中肝素量不同而不同。c:Perclose缝合器法：严格按操作规范缝合穿刺点血管。④实验评估：记录止血时间，指从拔除动脉鞘管到穿刺部位无出血的时间；制动时间，指从手术结束到患者下地活动时间；观察有无血管并发症，包括穿刺部位局部血肿（直径 > 5 cm）、穿刺口渗血、假性动脉瘤、血栓形成、动静脉瘘、血管迷走反射等；计算止血成功率。 结果：共纳入观察患者436例，均进入结果分析。结果发现 Boomerang封堵器组止血成功率96.4%，Perclose缝合器组止血成功率90.5%；不论单纯冠状动脉造影还是介入治疗，两组患者与人工压迫法比较止血时间及下肢制动时间均显著缩短（P < 0.05，P < 0.01）；介入治疗中，Perclose缝合器血管并发症发生率为5.2%，Boomerang封堵器为5.7%，均较人工压迫组（14.7%）明显减少（P均< 0.05）。 结论：Perclose缝合器与Boomerang封堵器用于股动脉穿刺后止血迅速、有效、安全，止血时间、制动时间及血管并发症发生率均明显优于人工压迫法止血，且不存在特殊生物相容性问题。     

Focal stimulation of human peripheral nerve with the magnetic coil: a comparison with electrical stimulation

The hypothenar compound motor action potential (CMAP) response to ulnar nerve stimulation at the elbow was used as a test system in the human to compare excitations by a round magnetic coil (MC), 92 mm in outer diameter, and by electrical bipolar or tripolar stimulation. Optimal focality of excitation was obtained with the MC at 90 degrees to the extended arm and its plane parallel to the arm, i.e., an orthogonal-longitudinal orientation. Tangential orientation of the MC on the arm, i.e., laying it flat on the arm, powerfully excited additional structures. As expected from classical axonology, orthogonal-transverse orientations were the least effective. With orthogonal-longitudinal orientation and submaximal stimulation, the spread of excitation lateral to the median nerve at the wrist was of the order of 10-15 mm, the thickness of the MC being 12 mm. With the same orientation, the site of origin of the distally propagating impulse was estimated by comparing CMAP latencies to bipolar electrical (with cathode distal) and MC stimulation. Tripolar stimulation (with cathode intermediate) had no advantage over bipolar stimulation. The impulse originated 13-22 mm from the midpoint of the contacting edge. Rotating the MC through 180 degrees and thus reversing the field polarity did not significantly change the CMAP latency, indicating that the effective cathode and anode lay within a few mm of each other. Stimulating with a tilted MC resulted in a maximum CMAP when the orthogonal-longitudinal orientation failed to do so. A simple volume conductor model yielded a potential gradient of the right order of magnitude (35 mV/mm) when the MC stimulator output was 25% of maximum, i.e., a little above threshold for exciting ulnar motor axons.     

A comparison of the hemodynamic effects produced by electrical stimulation of subnuclei of the paraventricular nucleus

The paraventricular nucleus of the hypothalamus (PVN) is composed of magnocellular and parvocellular subdivisions. Magnocellular neurosecretory neurons project to the neurohypophysis while parvocellular neurons send monosynaptic axonal projections to autonomic regulatory areas in the brainstem and spinal cord. In the present study, we investigated the hemodynamic effects produced by selective magnocellular or parvocellular stimulation. In urethane anesthetized rats with intact baroreflexes, magnocellular and parvocellular stimulation produced only slight differences in hemodynamic responses, however, following acute sinoaortic denervation a clear difference was observed. Parvocellular stimulation produced an increase in arterial pressure and vasoconstriction in gut, kidney and skeletal muscle. Magnocellular stimulation produced little effect on arterial pressure and marked vasodilation in the hindquarters. Blockade of peripheral vasopressin vascular receptors did not affect the vasoconstrictor response produced by stimulation of PVN. These data are consistent with the hypothesis that the long descending neural projections of the parvocellular PVN subserve a selective vasoconstrictor function.     

Focal stimulation of human cerebral cortex with the magnetic coil: a comparison with electrical stimulation

Percutaneous stimulation of human motor cortex electrically (focal anode) and with magnetic coils (MCs) of various designs is compared. The theoretical prediction was confirmed that positioning the standard round MC laterally and orientating it more towards the vertical induces an electric field appropriate for directly exciting corticospinal neurons (cf., the conventional tangential orientation at the vertex). Thus, during voluntary contraction, minimal latency compound motor action potentials (CMAPs) in contralateral arm were elicited both by focal anodic and appropriately orientated MC stimulation. Conduction time from motor cortex to motoneuron was estimated by subtracting peripheral conduction time and monosynaptic delay at the motoneuron from the overall CMAP latency, yielding an estimated corticospinal conduction velocity as high as 66 m/sec. Discontinuous latency variations observed in population CMAPs or individual motor units approximated mono- or polysynaptic cortical synaptic delays and, therefore, are attributed to the intervals between direct and early, or late indirect corticospinal discharges. A TV computer system was used to track movements of individual digits and the hand following MC stimulation. An appropriately orientated MC readily elicited movements predominantly of a single digit, implying focal activation of motor cortex. A double square and a small pointed MC proved especially convenient for eliciting reproducibly single digit movements. Stronger stimulation revealed a topographical gradient in the responses of the different digits. Responses to a given MC stimulus a little above threshold were variable in amplitude, which could not be explained by the relationship of stimulus to phase of the cardiac or respiratory cycle. Overall, our findings indicate the importance of appropriately orientating a standard round MC and using a specially designed MC to obtain the various types of motor response to stimulation of cerebral cortex.     

Sympathetic neurograms showing characteristics of both muscle and skin sympathetic nerve activity in a case with pure autonomic failure

Clinical Autonomic Research -     

A comparison of the effects of intrathecally administered 5-hydroxytryptamine and thyrotropin-releasing hormone on renal and muscle sympathetic nerve activity

Thyrotropin-releasing hormone (TRH) has been shown to coexist with 5-hydroxytryptamine (5-HT) in spinally projecting raphe neurones, some of which terminate in the sympathetic nuclei of the spinal cord. In an attempt to mimic the actions of these neurones, the effects of intrathecal administration of 5-HT was compared to that of TRH on activity in two sympathetic postganglionic nerves, the renal nerve and sympathetic fibres to skeletal muscle of the hind limb. In chloralose-urethane anaesthetised rats intrathecal infusion of TRH at the T9 level in doses of 5-30 micrograms increased activity in renal nerve as did low doses (20-100 micrograms) of 5-HT. In contrast, intrathecal infusion of TRH in doses of 5-30 micrograms and 5-HT in doses of 20-800 micrograms at L4 level decreased activity in sympathetic fibres to muscle. The results show that TRH, unlike 5-HT, has an excitatory but not an inhibitory action on renal sympathetic activity whereas both substances have only an inhibitory action on muscle sympathetic activity.     

Sympathetic and afferent somata projecting in hindlimb nerves and the anatomical organization of the lumbar sympathetic nervous system of the rat

The anatomy of the sympathetic pathways from the spinal cord to the lumbar sympathetic trunk and the inferior mesenteric ganglion was studied systematically in the rat. Details of the arrangements of white and gray rami communicantes, sympathetic trunk ganglia, the intermesenteric nerve, and the lumbar splanchnic nerves are summarized. A modified nomenclature for the segmental ganglia of the paravertebral sympathetic chain is proposed. Cell bodies of sensory and sympathetic axons projecting to the skin and skeletal muscle of the rat hindlimb were labeled retrogradely with horseradish peroxidase (HRP) in order to study numbers, segmental distribution, and location of the somata of these neurons quantitatively. HRP was applied to the nerves supplying skeletal muscle (gastrocnemius-soleus, GS), hairy skin (sural, SU; saphenous, SA) and to a mixed nerve (tibial, TI). All sensory somata and 96.4% of the sympathetic cell bodies were located ipsilaterally. Sensory somata were commonly restricted to two adjacent dorsal root ganglia (usually L3-4 for SA; L4-5 for GS, TI; L5-6 for SU). Although the sympathetic somata were more widely distributed rostrocaudally (four to six segments), their maximum was always located one or two segments more cranially than the sensory outflow, i.e., corresponding to the rami communicantes grisei. From the data, it is estimated that 420 sympathetic and 530 afferent neurons project into GS, 590 and 3,610 into SU, 920 and 3,750 into SA, and 1,070 and 5,760 into TI. These absolute neuron numbers are compared with electron microscopic fiber counts from the literature.