Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “REFLEX”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,351 records · Page 75Linked to original sources
PubMed1999

Acoustic reflex detection using wide-band acoustic reflectance, admittance, and power measurements.

The measurement of the acoustic reflex threshold is a basic component of the diagnostic audiological test battery that may subject patients to potentially harmful sound pressures. A wide-band acoustic impedance and reflectance system (D. H. Keefe, R. Ling, & J. C. Bulen, 1992) was investigated as a means of obtaining reflex thresholds at a reduced level and as a means of providing a more complete characterization of the reflex than current clinical methods provide. Reflex thresholds obtained by measuring changes in wide-band admittance, reflectance, and power were at least 8 dB lower than those obtained with the standard clinical technique. These reflex-induced changes were accounted for by a simple oscillator model of the middle ear, assuming that the acoustic reflex results in an increase in stiffness. The results support further investigation of reflectance-based measures of the acoustic reflex as a clinical tool and as a means of studying the reflex mechanism.

Acoustic Impedance Tests↗
PubMed2001

Effect of dexmedetomidine, an alpha2-adrenoceptor agonist, on human pupillary reflexes during general anaesthesia.

AIMS: To test the hypothesis that the alpha2-adrenergic agonist, dexmedetomidine, dilates the pupil and does not alter the pupillary light reflex of anaesthetized patients. METHODS: Eight volunteers were administered general anaesthesia with propofol, nitrous oxide and alfentanil. One hour and 25 min after induction of anaesthesia, a 45 min infusion of dexmedetomidine was begun, targeting a plasma concentration of 0.6 ng x ml(-1). Pupil size, pupillary light reflex amplitude, light reflex recovery time, and reflex dilation were measured before and during dexmedetomidine infusion. RESULTS: Dexmedetomidine produced no change in pupil size and light reflex recovery time, increased the light reflex from 0.30 +/- 0.14 to 0.37 +/- 0.12 mm and significantly reduced pupillary reflex dilation by 72 +/- 62%. CONCLUSIONS: These pupillary effects of dexmedetomidine in humans are difficult to reconcile with the findings obtained in cats and rats that have demonstrated a direct inhibitory effect of alpha2-adrenergic agonists on the pupilloconstrictor nucleus. The increase in the magnitude of the light reflex in response to dexmedetomidine does not necessarily involve an anxiolytic mechanism.

Adrenergic alpha-2 Receptor Agonists↗
PubMed1999

Temporal changes in airway protective reflexes elicited by an endotracheal tube in surgical patients anaesthetized with sevoflurane.

In order to elucidate temporal changes in airway reflex responses to prolonged tracheal intubation, 14 patients anaesthetized with sevoflurane were studied. In each spontaneously breathing patient with an endotracheal tube in place, the end-tidal concentration of sevoflurane was slowly decreased from the initial value of 1.3% until signs of airway irritation were observed. The value of end-tidal sevoflurane concentration at which the airway reflexes occurred (T(ar)) and the types of airway reflex response elicited at onset of airway reflex response were determined during the periods immediately before (presurgical period) and after surgery (post-surgical period), with an interval ranging from 2 to 7 h between the two periods. There was no significant difference in the values of T(ar) between the presurgical period (0.6 +/- 0.3%, mean +/- SD) and the post-surgical period (0.7 +/- 0.1%). There was a considerable difference in the type of airway reflexes elicited during the two different periods; the initial responses during the presurgical period were the apnoeic reflex and/or forceful expiratory efforts, whereas the initial response during the post-surgical period, in the majority of patients, was the swallowing reflex. Our results indicate that there may be adaptation mechanisms responsible for temporal changes in airway protective reflexes after prolonged endotracheal intubation in surgical patients.

Adaptation, Physiological↗
PubMed2000

Relation between incidence of pneumonia and protective reflexes in post-stroke patients with oral or tube feeding.

OBJECTIVES: Although attenuated protective reflexes have been implicated in the development of aspiration pneumonia, the relation between the incidence of pneumonia and the state of these reflexes has not been investigated. Furthermore, the role of feeding tube placement in preventing pneumonia in patients with attenuated protective reflexes is unknown. We studied the relationship between the incidence of pneumonia and the state of cough and swallowing reflexes in post-stroke patients with oral or tube feeding. DESIGN: The incidence of pneumonia was prospectively analysed for 1 year in three groups of post-stroke patients on the basis of the following clinical conditions: oral feeding without dysphagia (n = 43); oral feeding with dysphagia (n = 48); and nasogastric tube feeding with dysphagia (n = 52). We also studied the incidence of pneumonia in bedridden patients with nasogastric tube feeding (n = 14). Before the start of the study, the swallowing and cough reflexes of each patient were measured. The swallowing reflex was evaluated according to latency of response, which was timed from the injection of 1 mL of distilled water into the pharynx through a nasal catheter to the onset of swallowing. The cough threshold of citric acid aerosols was defined as the concentration at which the patient coughed five times. RESULTS.;: The incidence of pneumonia was observed in patients having both a latency of response longer than 5 s and a cough threshold for citric acid higher than a concentration of 1.35 (log mg mL-1). The incidence of pneumonia was significantly higher in patients with oral feeding than in those with tube feeding (54.3 vs. 13.2%, P < 0.001). In bedridden patients with tube feeding, the latency of response was longer than 20 s and no patient coughed at the highest concentration of citric acid. The incidence of pneumonia was 64.3% in such patients. CONCLUSIONS: The state of protective reflexes had a significant relation to the incidence of pneumonia. Feeding tube placement may have a beneficial role in preventing aspiration pneumonia in mildly or moderately disabled post-stroke patients with attenuated protective reflexes. Bedridden patients who were tube-fed had the highest incidence of pneumonia.

Aged↗
PubMed1997

Relaxant effects of potassium-channel openers on normal and hyper-reflexic detrusor muscle.

OBJECTIVE: To compare the effects of the potassium-channel openers, levcromakalim and YM934, in isolated human detrusor muscle from normal and hyper-reflexic bladders. MATERIALS AND METHODS: Strips of human detrusor muscle from normal and hyper-reflexic bladder were pre-contracted with carbachol and the potassium-channel openers (0.1-0.3 mumol/L) were added cumulatively to the organ baths. Other strips were field-stimulated at frequencies producing 25% and 75% of the maximum response to field stimulation. Contractions could be abolished by atropine (10 mumol/L) and tetrodotoxin (1 mumol/L). RESULTS: The hyper-reflexic bladder was significantly more sensitive to carbachol than the normal bladder but the maximum response was significantly lower in the hyper-reflexic tissue. There was no significant difference between the potency of the potassium-channel openers in normal and hyper-reflexic detrusor muscle. Hyper-reflexic bladder was significantly more sensitive to electrical field stimulation than was normal bladder: maximum responses to field stimulation were not significantly different. Concentration-response curves for the potassium-channel openers were displaced to the left in hyper-reflexic bladder at both 25% and 75% maximum frequencies: however, only with levcromakalim at 75% of the maximum frequency was the shift significant. CONCLUSION: The greater sensitivity of hyper-reflexic bladder to carbachol and field stimulation supports existing evidence for post-junctional supersensitivity in detrusor instability. The results of this study also suggest that there are no appreciable changes in KATP channel function in the unstable bladder.

Benzopyrans↗
PubMed2002

Measuring various sizes of H-reflex while monitoring the stimulus condition.

The purpose of this study was to assess the usefulness of a new technique that measured various sizes of the soleus H-reflex, while monitoring the stimulus condition. Eight healthy volunteers participated in this experiment. In the new technique, an above-motor-threshold conditioning stimulus was given to the tibial nerve 10-12 ms after a below-motor-threshold test stimulus. The conditioning stimulus evoked a direct M-wave, which was followed by a test-stimulus-evoked H-reflex. This reflex was followed by a conditioning stimulus-evoked H-reflex. The amount of the voluntary-contraction-induced facilitation of the H-reflex was similar for both the new technique and conventional technique, in which an above-motor-threshold test stimulus was given without a conditioning stimulus. Using the new technique, we found that the amount of facilitation increased linearly with the size of the test H-reflex. This technique allows us to evoke various sizes of H-reflex while monitoring a stimulus condition, and is useful for measuring H-reflexes during voluntary movement.

Adolescent↗
PubMed2006

Middle-finger reflex.

A new reflex is described: middle-finger extensor reflex elicited by percussion of tendon insertion of musculus extensor digitorum communis in forearm. Following percussion using a reflex hammer, two EMG responses from the belly of the muscle were recorded: a short latency monosynaptic reflex with a latency of 31.4 +/- 1.5 ms (M1), and a long-latency middle-finger reflex with a mean latency of 64.8 +/- 6.31 ms (M2), the former being a monosynaptic extensor reflex, and the latter belonging to a spino-cortico-spinal reflex circuitry. It was suggested that the middle-finger extensor reflex elicited by radial nerve afferents and efferents (C7-C8) would be of clinical and theoretical importance.

Afferent Pathways↗
PubMed2005

Use of a motorized bicycle exercise trainer to normalize frequency-dependent habituation of the H-reflex in spinal cord injury.

BACKGROUND/OBJECTIVES: Spasticity in patients with spinal cord injury (SCI) is difficult to manage. Exercise and stretching is advocated as a management tool, but these activities are difficult to perform for most patients as a result of multiple barriers. This report shows the effect of passive range-of-motion exercise in a walking-like pattern on frequency-dependent habituation of the H-reflex in the lower extremities of an individual with spastic tetraplegia due to SCI. METHODS: The participant, a man with a chronic ASIA B C7 SCI due to a gunshot wound, used a motorized bicycle exercise trainer (MBET) developed at the Jackson T. Stephens Spine & Neurosciences Institute at the University of Arkansas for Medical Sciences that could be operated from the individual's wheelchair. He used the MBET for 1 hour, 5 days a week, for 13 weeks. H-reflex habituation was tested at the beginning of the study and then periodically over the course of 17 weeks, including 4 weeks after exercise had ceased. RESULTS: Significant habituation of the H-reflex was evident beginning at the 10th week of training. The habituation in the H-reflex reached a normal level at 5- and 10-Hz frequencies at 12 weeks. Subjective assessment of spasticity indicated that it was significantly reduced. The H-reflex amplitude was maintained at normal levels during the remaining week of the course of exercise and for 2 additional weeks after exercise ceased. The H-reflex habituation, however, returned to near baseline when reassessed at week 17, 4 weeks after the exercise program had concluded. Subjective assessment indicated that spasticity also had returned to pretraining levels. CONCLUSIONS: Habituation of the H-reflex, and perhaps spasticity, can be managed by a routine passive range-of-motion exercise program using a MBET, but the exercise program may need to be continuous. The benefit of reduced medication for spasticity and possibly improved quality of life could be a motivating factor for an individual with SCI and spasticity to continue the program. Because of the low complexity of the program, ease of use, and small size, this system could be inexpensive and could be used by an individual in the home. Ongoing studies will determine the minimum amount of MBET training required for maintaining long-term H-reflex habituation.

Adult↗
PubMedDate not supplied

Drug-assisted effects on protective airway reflexes during out-of-hospital endotracheal intubation (preliminary report).

OBJECTIVE: Out-of-hospital rescuers often use drug-assisted intubation (DAI) to facilitate endotracheal intubation (ETI) of nonarrest patients. However, the relationship between the ablation of individual protective airway reflexes and resulting DAI success has not been defined. We sought to describe the relationship between the depression or ablation of protective airway reflexes and DAI success. METHODS: We analyzed data from a prospective multicenter trial. Rescuers from 42 emergency medical services systems reported clinical ETI data using standardized reporting forms. We analyzed the subset receiving sedative and/or neuromuscular blocking agents to facilitate ETI. We defined successful ETI as intratracheal placement of the endotracheal tube on the last ETI attempt. Rescuers reported the presence and ablation of six protective airway reflexes, including the presence of a gag, trismus, inadequate relaxation, combativeness, laryngospasm, and seizure/myoclonus. We examined the relationship between protective reflex ablation and DAI success. RESULTS: Of 1,953 ETIs, 208 (10.7%) used DAI (128 sedation only, 80 neuromuscular blocking agents/rapid sequence intubation). Successful DAI was associated with ablation of gag reflex (odds ratio [OR], 12.7; 95% confidence interval [CI] 3.7 to 46.2), clenched jaw/trismus (OR, 54.4; 95% CI, 11.1 to 292.4), inadequate relaxation (OR, 16.3; 95% CI, 3.7 to 96.4), and combativeness (OR, 10.2; 95% CI, 1.5 to 76.8). Successful DAI was associated with the total number of ablated protective reflexes (p < 0.001). CONCLUSIONS: The ablation of selected and the total number of protective airway reflexes was associated with DAI success. Successful ablation of protective airway reflexes should be considered when attempting to characterize DAI performance or the effectiveness of specific drug facilitation regimens.

Emergency Medical Services↗
PubMed1999

Operant conditioning of H-reflex increase in spinal cord--injured rats.

Operant conditioning of the spinal stretch reflex or its electrical analog, the H-reflex, is a new model for exploring the mechanisms of long-term supraspinal control over spinal cord function. Primates and rats can gradually increase (HRup conditioning mode) or decrease (HRdown conditioning mode) the H-reflex when reward is based on H-reflex amplitude. An earlier study indicated that HRdown conditioning of the soleus H-reflex in rats is impaired following contusion injury to thoracic spinal cord. The extent of impairment was correlated with the percent of white matter lost at the injury site. The present study investigated the effects of spinal cord injury on HRup conditioning. Soleus H-reflexes were elicited and recorded with chronically implanted electrodes from 14 rats that had been subjected to calibrated contusion injuries to the spinal cord at T8. At the lesion epicenter, 12-39% of the white matter remained. After control-mode data were collected, each rat was exposed to the HRup conditioning mode for 50 days. Final H-reflex amplitudes after HRup conditioning averaged 112% (+/-22% SD) of control. This value was significantly smaller than that for 13 normal rats exposed to HRup conditioning, in which final amplitude averaged 153% (+/-51%) SD of control. As previously reported for HRdown conditioning after spinal cord injury, success was inversely correlated with the severity of the injury as assessed by white matter preservation and by time to return of bladder function. HRup and HRdown conditioning are similarly sensitive to injury. These results further demonstrate that H-reflex conditioning is a sensitive measure of the long-term effects of injury on supraspinal control over spinal cord functions and could prove a valuable measure of therapeutic efficacy.

Animals↗
PubMed2006

Corticospinal tract transection permanently abolishes H-reflex down-conditioning in rats.

Previous studies have shown that corticospinal tract (CST) transection, but not transection of other major spinal cord tracts, prevents down-conditioning of the H-reflex, the electrical analog of the spinal stretch reflex. This study set out to determine whether the loss of the capacity for H-reflex down-conditioning caused by CST transection is permanent. Female Sprague-Dawley rats received CST, lateral column (LC), or dorsal column ascending tract (DA) transection at T8-9; 9-10 months later, they were exposed to the H-reflex down-conditioning protocol for 50 days. In the LC and DA rats, H-reflex size fell to 60 (+/- 9 SEM)% and 60 (+/- 19)%, respectively, of its initial size. This down-conditioning was comparable to that of normal rats. In contrast, H-reflex size in the CST rats rose to 170 (+/- 42)% of its initial size. A similar rise does not occur in rats exposed to down-conditioning shortly after CST transection. These results indicate that CST transection permanently eliminates the capacity for H-reflex down-conditioning and has gradual long-term effects on sensorimotor cortex function. They imply that H-reflex down-conditioning can be a reliable measure of CST function for long-term studies of the effects of spinal cord injury and/or for evaluations of the efficacy of experimental therapeutic procedures, such as those intended to promote CST regeneration. The results also suggest that the role of sensorimotor cortex in down-conditioning extends beyond generation of the essential CST activity.

Animals↗
PubMed2002

Interlimb reflexes and synaptic plasticity become evident months after human spinal cord injury.

Persons with long-standing injury to the cervical spinal cord resulting in complete or partial paralysis typically develop a wide spectrum of involuntary movements in muscles receiving innervation caudal to the level of injury. We have previously shown that these movements include brief and discrete contraction of muscles in the hand and forearm in response to innocuous sensory stimulation to the feet and legs, but we have been unable to replicate these interlimb reflexes in able- bodied subjects. Properties of these muscle responses indicate that the synaptic contacts between ascending sensory fibres and motor neurones of the cervical enlargement are more efficacious than normal. If these connections are present at all times, and require the more rostrally-placed spinal cord injury to allow their emergence, one might expect their appearance relatively soon following injury, as has been shown for studies of 'latent' synapses. Conversely, delayed appearance of these interlimb reflexes would suggest either the development of new synaptic connections or a profound strengthening of existing circuits in the cervical spinal cord due to a combination of afferent target loss and motor neurone denervation from motor tracts originating rostral to the injury site. In this study, we used repeated examinations of persons with acute injury to the cervical spinal cord to examine the time post-injury at which interlimb reflexes are first seen. Using tibial nerve stimulation at the knee as a screening test, a total of 24 subjects were found to develop interlimb reflexes following spinal cord injury. Latencies between stimulation and EMG were as brief as 32 ms for muscles of the forearm and 44 ms for muscles in the hand. These minimal delays all but rule out a supraspinal route for these interlimb reflexes. Interlimb reflexes first became evident no sooner than approximately 6 months following injury, and in some individuals were not seen until well over 1 year post-injury. Enhanced lower limb segmental excitability had emerged in nearly all of these subjects weeks or months prior to the first appearance of interlimb reflexes, arguing against a manifestation of traditional post-traumatic spasticity as a basis for this activity. This prolonged delay between time of injury and emergence of interlimb reflex activity lends support to the hypothesis that this activity represents an example of plasticity-and perhaps 'regenerative sprouting'-in the human spinal cord following traumatic injury.

Adolescent↗
PubMed1992

Effect of air-splint application on soleus muscle motoneuron reflex excitability in nondisabled subjects and subjects with cerebrovascular accidents.

We investigated the effect of air-splint pressure on soleus muscle motoneuron reflex excitability in 18 nondisabled subjects with no history of neurological disease and 8 subjects with cerebrovascular accidents (CVAs). Motoneuron reflex excitability was assessed by measuring the percentage of amplitude (peak-to-peak measurement) change in the Hoffman reflex (H-reflex). Pressure was applied for 5 minutes, after which the air-splint was deflated. Ten H-reflexes were recorded and averaged for each subject before pressure application to obtain a baseline value. H-reflexes were also recorded at set intervals during and after pressure application. Two-way analyses of variance for repeated measures were used to compare each group's pressure and postpressure measurements with the baseline value. Significant F tests were followed by post hoc t tests. Analyses of variance were used to compare the nondisabled subjects' H-reflex recordings with those obtained for the subjects with CVAs. The nondisabled subjects demonstrated reductions of 55% at 1 minute, 52% at 3 minutes, and 40% at the fifth minute of pressure application. The postpressure measurements showed increases in the reflex amplitude at 1 and 3 minutes postpressure; however, by the fifth minute, the amplitude was not different from the baseline value. The subjects with CVAs demonstrated reductions of 41% at 1 minute, 48% at 3 minutes, and 52% at 5 minutes of pressure application. None of the postpressure measurements, however, were statistically different from the baseline value. A statistically significant difference was demonstrated between the nondisabled subjects and the subjects with CVAs at the first minute of pressure release.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2003

Mechanism of pupillary reflex dilation in awake volunteers and in organ donors.

BACKGROUND: The mechanism of reflex pupillary dilation was investigated in eight patients who were declared brain dead after rupture of intracranial vascular malformations and in eight awake volunteers. The authors hypothesized that the reflex was primarily a spinal sympathetic reflex that would be blocked by topical application of the alpha1-adrenergic blocking agent dapiprazole and that it would be present in organ donors with intact spinal reflexes and no history of hypoxia. METHODS: In volunteers, pupil size was measured with an infrared pupillometer while brief painful electric stimuli were delivered to the finger. Pain was assessed with a visual analog scale and adjusted with each volunteer to equal 3 on a visual analog scale of 0-10. Subjects were studied before and after topical application of the alpha1-adrenergic antagonist dapiprazole. In organ donors, the authors measured pupil size after high-intensity tetanic electric stimulation and in dapiprazole-blocked and -unblocked pupils after surgically induced nociception. RESULTS: In volunteers, the pupil dilated 0.43 +/- 0.23 mm after nociceptive stimuli. Dapiprazole eyedrops blocked this dilation, confirming that the reflex in awake humans is primarily a sympathetic reflex. Baseline diameters were 5.7 +/- 0.5 mm before dapiprazole and 4.1 +/- 0.9 mm after dapiprazole. In organ donors, a tetanic electric current failed to dilate the pupil, whereas the skin incision dilated the pupil 0.4 +/- 0.4 mm, but this dilation was not blocked by dapiprazole. CONCLUSION: The authors conclude that pupillary reflex dilation, as it is clinically performed in awake subjects by stimulating somatic nociceptors, is a sympathetic reflex. Because it is not present in organ donors, the neural pathway must require a supraspinal component for completion.

Adult↗
PubMedDate not supplied

Central loop of the H reflex. Normal value and use in S1 radiculopathy.

The H reflex in the S1 spinal nerve has been used in electrodiagnosis of S1 radiculopathy for several years. Direct stimulation of the S1 spinal nerve has provided more complete information about the H reflex pathway by dividing it into its peripheral and central (or spinal) conduction portions. A previous study compared spinal nerve latency with the H reflex latency, demonstrating an abnormal S1 ratio in subjects with S1 radiculopathy, thereby suggesting slowing within the spinal segment of the nerve. No study, however, has established a normal value for the central (spinal) portion of the H reflex. We electrodiagnostically tested 20 subjects with normal clinical neurologic and musculoskeletal examinations to define a normal sample of the central loop of the H reflex in the S1 spinal nerve. The peak latencies of the M and H reflex responses were measured after a single stimulus to the S1 spinal nerve. The data obtained established 7 +/- 0.3 ms as the normal value for the interpotential latency difference (central loop) of the H reflex in the S1 spinal nerve in healthy subjects. Six patients with clinical and electromyographic evidence of S1 radiculopathy all had central loop latencies of > 8 ms. The normal value of the central loop of the H reflex suggested in this pilot investigation may, therefore, be used to allow for earlier and more accurate diagnosis of an acute S1 radiculopathy.

Adult↗
PubMed1988

Observations on the acoustic reflex threshold in institutionalized retarded adults taking mellaril and/or thorazine.

The present study was designed to investigate whether mellaril and thorazine, when used alone and in combination with other medications by mentally retarded clients, either abolish acoustic reflexes or compromise estimates of hearing sensitivity based on acoustic reflex measures. Acoustic reflex thresholds were determined in 35 normal-hearing institutionalized mentally retarded subjects who were regular users of the medications under investigation. Five sensitivity prediction methods based on acoustic reflex thresholds were applied to the data. The results of the study showed that acoustic reflexes were present in most subjects. However, the accuracy of all the acoustic reflex-based sensitivity prediction methods was quite poor with greatly exaggerated predictions of hearing loss. The methods based solely on noise reflex thresholds provided better accuracy than those based on noise-tone differences. In general, the accuracy of the prediction methods decreased as the number of medications used by the subjects increased. It is argued that the results provide evidence for reticular activating system mediation of acoustic reflex activity.

Adult↗
PubMedDate not supplied

Suppression of reflex tachycardia following alpha-adrenoceptor blockade in conscious dogs: comparison of urapidil with prazosin.

The effects of the alpha-adrenoceptor antagonists urapidil and prazosin were compared as to their ability to suppress or enhance baroreceptor-induced reflex changes in heart rate in conscious dogs. Bradykinin was injected as an intravenous bolus to elicit a vasodepressor response and reflex tachycardia, and angiotensin II was utilized to produce opposite effects via baroreceptor activation. Urapidil, which is an alpha 1- and alpha 2-antagonist, was infused intravenously at 2 and 5 mg/kg, and suppressed reflex tachycardia elicited by bradykinin at both dose levels. The suppression of reflex tachycardia elicited by bradykinin was not evident with intravenous prazosin (0.25 and 0.625 mg/kg), an alpha 1-antagonist. Reflex bradycardia elicited by angiotensin was not affected by urapidil but was enhanced by prazosin. Therefore, urapidil may have a selective effect in suppressing cardiac sympathetic reflexes with no apparent effect on vagal reflexes. Both urapidil and prazosin produced similar decreases in arterial blood pressure with no long-term effects on heart rate, and the degree of alpha-receptor postjunctional blockade by both agents was judged to be equivalent, as determined by intravenous phenylephrine injection. The suppression of reflex tachycardia by urapidil could be eliminated by guanethidine pretreatment, indicating that a cardiosympathoinhibitory effect by urapidil was involved.

Adrenergic alpha-Antagonists↗
PubMed2000

Electrical stimulation of the rat lumbar spine induces reflex action potentials in the nerves to the lower abdomen.

STUDY DESIGN: The distribution of the nerve action potentials reflexively elicited by electrical stimulation of the lumbar spine was investigated in rats. OBJECTIVES: To elucidate the relation between the lumbar spine and other body regions that compose the spinal reflex. SUMMARY OF BACKGROUND DATA: The hypothesis was that the ventral portion of the L5-L6 disc spatially corresponds to the groin. METHODS: In Experiments 1 and 2, wire electrodes were placed 1) in the ventral and dorsal portions of the disc, facet joint, and muscle fascia at L5-L6, and 2) in the ventral portions of L3-L4, L4-L5, L5-L6, and L6-S discs. A needle electrode was inserted in the L5-L6 disc by 0.4-mm increments, and action potentials were serially recorded from the genitofemoral nerve. RESULTS: Experiments 1 and 2: Reflex action potentials were elicited in the iliohypogastric (T13 and L1), ilioinguinal (L1), and genitofemoral (L2) nerves. Experiment 1: Stimulation of the disc induced reflex discharges significantly more frequently than stimulation of the facet joint and muscle fascia. Experiment 2: The more cranial the disc stimulated, the more frequently the reflex discharge was induced in the iliohypogastric nerve. Experiment 3: The depth of stimulation did not influence the size of the reflex action potential. CONCLUSIONS: Electrical stimulation of the lumbar disc and facet joint induced reflex discharges in the nerves to the lower abdominal regions. It was postulated that the reflex discharges are related to muscle contraction resulting in referred pain in the loin and groin.

Abdominal Muscles↗