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Journal of Applied Physiology... Dec 2001The distribution of the reflex effects of isometric exercise on cutaneous vasomotor and sudomotor function is not clear. We examined the effects of isometric exercise by...
The distribution of the reflex effects of isometric exercise on cutaneous vasomotor and sudomotor function is not clear. We examined the effects of isometric exercise by different muscle masses on skin blood flow (SkBF) and sweat rate (SR) in nonglabrous skin and in glabrous skin. The latter contains arteriovenous anastomoses (AVAs), which cause large fluctuations in SkBF. SkBF was measured by laser-Doppler flowmetry (LDF) and reported as cutaneous vascular conductance (CVC; LDF/mean arterial pressure). SR was measured by capacitance hygrometry. LDF and SR were measured at the sole, palm, forearm, and ventral leg during separate bouts of isometric handgrip (IHG) and isometric leg extension (ILE). CVC and its standard deviation decreased significantly during IHG and ILE in the palm and sole (P < 0.05) but not in the forearm or leg (P > 0.05). Only palmar SR increased significantly during IHG and ILE (P < 0.05). We conclude that the major reflex influences of isometric exercise on the skin include AVAs and palmar sweat glands and that this is true for both arm and leg exercise.
Topics: Adult; Exercise; Foot; Hand; Hand Strength; Humans; Isometric Contraction; Laser-Doppler Flowmetry; Leg; Male; Regional Blood Flow; Skin; Sweating; Vascular Resistance
PubMed: 11717209
DOI: 10.1152/jappl.2001.91.6.2487 -
The Journal of Investigative Dermatology Nov 1999A main drawback of 20-25 MHz ultrasound units for skin imaging is their limited resolution. We used a transducer with a center frequency of 95 MHz and a resolution of...
A main drawback of 20-25 MHz ultrasound units for skin imaging is their limited resolution. We used a transducer with a center frequency of 95 MHz and a resolution of 8.5 microm axially and 27 microm laterally - an almost 10-fold increase compared with 20 MHz. By means of a new scanning technology we reached a depth of field of 3.2 mm. We examined normal palmar skin, normal glabrous skin on the abdomen, the upper back, the calf and the dorsal forearm, and 35 lesions of psoriasis vulgaris. From 11 psoriatic plaques biopsies were taken for correlation with the sonograms. In normal palmar skin, the horny layer is represented as an echopoor band below the skin entry echo, traversed by echorich coils, which correspond to eccrine sweat gland ducts. The thickness of this band significantly increases after occlusive application of petrolatum. Its lower border is defined by an echorich line, representing the stratum corneum/stratum Malpighii-interface. Underneath, a second echopoor band is visible, which corresponds to the viable epidermis plus the papillary dermis, bordered by the scattered echo reflexes of the reticular dermis. This band is also visible in glabrous skin; however, the stratum corneum cannot be detected. In psoriatic lesions, the thickened horny layer appears echorich; after application of petrolatum, its echodensity decreases. Below, the acanthotic epidermis plus the dermis with the inflammatory infiltrate are represented as an echopoor band. There is an excellent correlation between the sonometric thickness of this band and the histometric thickness of the acanthosis plus the infiltrated dermis. Our results show that 100 MHz sonography is a valuable tool for in vivo examination of the upper skin layers.
Topics: Adult; Aged; Female; Fingers; Humans; Male; Middle Aged; Psoriasis; Skin; Skin Physiological Phenomena; Thigh; Ultrasonography
PubMed: 10571740
DOI: 10.1046/j.1523-1747.1999.00795.x -
British Journal of Clinical Pharmacology Jun 1997Hyoscine (scopolamine), which is effective in the prophylaxis of motion sickness, shows similar binding affinities to all of the five known muscarinic receptor... (Clinical Trial)
Clinical Trial Comparative Study
AIMS
Hyoscine (scopolamine), which is effective in the prophylaxis of motion sickness, shows similar binding affinities to all of the five known muscarinic receptor sub-types. The effectiveness of hyoscine was compared with zamifenacin (UK-76654), which binds selectively to the muscarinic M3 and m5 receptors.
METHODS
Eighteen subjects received hyoscine hydrobromide 0.6 mg, zamifenacin 20 mg, or placebo (double-blind cross-over design). Sessions were 1 week apart and the drug (oral) was given 90 min prior to a motion sickness test. Motion sickness was elicited by cross-coupled stimulation on a turntable. The rotational velocity was incremented by 2 degrees s-1 every 30 s, and a sequence (seq) of eight head movements of 45 degrees was completed every 30 s. Motion tolerance was assessed as the number of sequences of head movement required to achieve moderate nausea. Pulse rate was recorded before and at 1 and 2 h after drug administration. Skin conductance activity in the frequency band 0.005-0.48 Hz, an index of sweat gland activity, was measured using Ag/AgCl electrodes on the palmar surfaces of fingers and across the forehead.
RESULTS
Both zamifenacin and hyoscine produced an increase in tolerance to the motion challenge (P < 0.01) with no significant difference between the two drugs (5.0 +/- 1.6 vs 5.7 +/- 1.6 seqs. respectively, mean +/- s.e.mean). Compared with placebo or zamifenacin, pulse rate fell following hyoscine administration (9 beats min-1, P < 0.01). Skin conductance was reduced following hyoscine compared with zamifenacin or placebo (P < 0.001).
CONCLUSIONS
These results suggest that compounds with selective M3 and/or m5 antagonism possess activity against motion sickness. Antagonism at these receptors may be the basis of the anti-motion sickness action of hyoscine.
Topics: Adult; Analysis of Variance; Binding, Competitive; Cross-Over Studies; Dioxoles; Double-Blind Method; Electrodes; Galvanic Skin Response; Heart Rate; Humans; Male; Middle Aged; Motion Sickness; Muscarinic Antagonists; Nausea; Piperidines; Psychomotor Performance; Receptors, Muscarinic; Rotation; Scopolamine; Sweat Glands
PubMed: 9205824
DOI: 10.1046/j.1365-2125.1997.00606.x -
European Journal of Clinical... Jul 1995Microvascular research is seriously hampered by the great temporal and spatial variability of the measured skin blood flow and variation in sympathetic vasomotor...
Microvascular research is seriously hampered by the great temporal and spatial variability of the measured skin blood flow and variation in sympathetic vasomotor reflexes within and between persons. Therefore skin vasomotor reflexes were studied before and after ulnar nerve blockade within the same person, resulting in a temporal complete denervation of the fifth finger and partial denervation of the fourth finger. Skin temperature and laser Doppler flux (LDF) were registrated to measure predominantly arteriovenous shuntflow. Measurements were performed on the palmar tip of the second and fifth finger in nine healthy volunteers, at baseline, and during a sympathetic reflex test (i.e. inspiratory gasp) and postural response test. Beat-to-beat digital blood pressure was recorded from the third and fourth finger by a Finapres device. Baseline capillary blood cell velocity (CBV) was measured at the nailfold of the second and the fifth finger. After ulnar blockade baseline skin temperature, LDF and CBV increased significantly, with respectively (mean +/- SE) 3.2 +/- 0.9 degrees C, 20.9 +/- 5.9 relative perfusion units and 0.79 +/- 0.40 mm-1 s. The percentage LDF decrease of the fifth finger during inspiratory gasp was 48.2 +/- 5.3% before and 3.1 +/- 0.9% after blockade. The postural response test showed a decrease in LDF of the fifth finger with no significant difference before and after blockade, respectively 12.3 +/- 14.7% and 8.0 +/- 2.7%, while no difference was found in the increase in digital blood pressure in the denervated fourth finger compared to both the same finger before blockade and to the third non-blocked finger.(ABSTRACT TRUNCATED AT 250 WORDS)
Topics: Blood Flow Velocity; Blood Pressure; Fingers; Humans; Inhalation; Lidocaine; Microcirculation; Posture; Reference Values; Reflex; Regional Blood Flow; Skin; Time Factors; Ulnar Nerve; Ultrasonography, Doppler; Vasoconstriction
PubMed: 7556370
DOI: 10.1111/j.1365-2362.1995.tb01738.x -
The Journal of Physiology Oct 19941. The possibility was investigated that, in man, some of the descending command for tonic voluntary wrist extension is transmitted to extensor motoneurones over a... (Clinical Trial)
Clinical Trial
1. The possibility was investigated that, in man, some of the descending command for tonic voluntary wrist extension is transmitted to extensor motoneurones over a non-monosynaptic pathway. 2. Stimulation of the cutaneous superficial radial nerve at 3 times perceptual threshold depressed the electromyogram (EMG) of extensor carpi radialis (ECR) and the discharge of single ECR motor units, both with a mean central delay of 4.2 ms. Such stimuli depressed the response to transcranial magnetic stimulation of the motor cortex, but had little effect on the H reflex. 3. The possibility that the relative sparing of the H reflex was due to an alteration in transmission of the afferent volley for the H reflex was excluded. 4. The central latency of the cutaneous-induced depression of the discharge of single motor units in biceps brachii (C5-C6) was shorter by about 1 ms than that of the more caudal wrist and finger extensor motor units. This suggests that the locus for the cutaneous-induced effects was spinal but above the cervical enlargement. 5. The pattern of EMG depression (evoked by superficial radial but not palmar stimuli, in wrist extensors but not wrist flexors) is that previously described for the presumed propriospinal system of human subjects. 6. It is concluded that a significant component of the voluntary command for tonic wrist extension reaches the relevant motoneurone pool via a non-monosynaptic pathway. It is suggested that the interposed neurones could be C3-C4 propriospinal neurones.
Topics: Action Potentials; Adult; Electric Stimulation; Electromyography; H-Reflex; Humans; Middle Aged; Motor Cortex; Motor Neurons; Movement; Muscles; Neurons, Afferent; Radial Nerve; Synaptic Transmission; Wrist
PubMed: 7853222
DOI: 10.1113/jphysiol.1994.sp020352 -
The Journal of Physiology Sep 19941. This study was designed to determine whether cutaneous receptors in the hand exert reflex effects on fusimotor neurones innervating relaxed muscles. Recordings were... (Clinical Trial)
Clinical Trial
1. This study was designed to determine whether cutaneous receptors in the hand exert reflex effects on fusimotor neurones innervating relaxed muscles. Recordings were made from fifty-four muscle spindle afferents in the radial nerve while the arm was held relaxed in a supporting frame. Cutaneous afferents were activated by trains of stimuli at non-noxious levels to the superficial radial nerve or to the palmar surface of the fingers. 2. For the population of muscle spindle afferents, the mean discharge rate was 7.1 +/- 6.4 Hz (range 0-24 Hz). Thirty-three per cent had no background discharge, and this occurred significantly more often in finger extensors than wrist extensors. 3. Trains of cutaneous stimuli produced no change in the discharge rates of the majority of spindle endings irrespective of whether the spindle afferent had a background discharge or was given one by muscle stretch. However, with two of forty afferents, the stimuli produced an increase in discharge at latencies of 135 and 155 ms. 4. With a further fourteen muscle spindle endings, the dynamic responses to stretch were measured 100-400 ms after the trains of cutaneous stimuli. For four spindle afferents there was a statistically significant change in the dynamic response to stretch occurring at conditioned-stretch intervals of 100-200 ms. For two afferents the dynamic response decreased by 17 and 26% and for two others it increased by about 24 and 37%. 5. While these results support the view that the level of background fusimotor drive is low in the relaxed state, they suggest that there is some dynamic fusimotor drive to completely relaxed muscles operating on the human hand, and that this drive can be altered reflexly by cutaneous afferent inputs from the hand.
Topics: Adult; Electric Stimulation; Electromyography; Female; Forearm; Hand; Humans; Male; Middle Aged; Muscle Relaxation; Muscle Spindles; Muscle, Skeletal; Neurons, Afferent; Reflex; Skin
PubMed: 7837105
DOI: 10.1113/jphysiol.1994.sp020313 -
The Journal of Physiology Jul 19901. In six subjects, H reflexes obtained in the flexor muscles in the forearm were inhibited by single motor threshold shocks to the radial nerve in the spiral groove....
1. In six subjects, H reflexes obtained in the flexor muscles in the forearm were inhibited by single motor threshold shocks to the radial nerve in the spiral groove. The first two phases of the inhibitory time course were studied: with intervals between the radial and median nerve shocks of -1 to +1 ms, and +5 to +30 ms. These two phases are thought to be due respectively to disynaptic inhibition between radial Ia afferents and flexor alpha-motoneurones, and to presynaptic inhibition of flexor Ia afferents. 2. Single or short trains (10 ms, 400 Hz) of cutaneous stimuli to the dorsal or palmar aspect of the proximal phalanx of the index finger or to the superficial radial nerve at the wrist, reduced the amount of presynaptic inhibition by 10-20%, but had no effect on the earlier disynaptic inhibition. Single stimuli to either side of the index finger or trains of stimuli to the ventral side, had no effect on the size of control H reflexes elicited alone. 3. Effects of cutaneous nerve shocks on presynaptic inhibition could be seen with stimuli as small as 1.5 x perceptual threshold. 4. Anaesthesia of the hand in one subject reversibly increased the amount of presynaptic inhibition and decreased the amount of disynaptic inhibition. 5. We conclude that, as in the cat, cutaneous input can modulate transmission in presynaptic inhibitory pathways in man.
Topics: Adult; Forearm; H-Reflex; Humans; Median Nerve; Muscles; Neural Inhibition; Neurons, Afferent; Radial Nerve; Sensory Thresholds; Skin; Synaptic Transmission; Time Factors
PubMed: 2172516
DOI: 10.1113/jphysiol.1990.sp018143 -
The Journal of Physiology Jan 19731. The precentral bank of the Rolandic fissure of the cortical arm area has been explored with extracellular micro-electrodes in primates (baboons and monkeys) under...
1. The precentral bank of the Rolandic fissure of the cortical arm area has been explored with extracellular micro-electrodes in primates (baboons and monkeys) under nitrous oxide and oxygen anaesthesia, supplemented by small doses of Parkesernyl(R) and chloralose. The results in baboons and monkeys were the same.2. Single units were classified as pyramidal tract neurones or non-pyramidal tract neurones according to their antidromic responsiveness to stimuli applied in the dorsolateral funiculus at C1-2.3. Responses to electrical stimulation of the deep (motor) radial nerve, the deep palmar (motor) branch of the ulnar nerve, and the superficial (cutaneous) radial nerve could be recorded in the majority of neurones of the motor cortex provided that short trains of strong stimuli were used. Minimal responses to muscle nerve stimulation were observed in a few neurones at 1.4 x group I threshold, but most units reacted only with higher stimulus intensities (2-3 x group I threshold).4. The latencies to peripheral nerve stimulation were measured from the first peak of the incoming volley recorded at the root entry zone. The mean response latencies of pyramidal tract cells were between 20 and 25 msec; non-pyramidal tract cells were activated at slightly shorter mean latencies, the difference being significant for superficial radial nerve stimulation only (4 msec). These latencies are more than twice as long as those recorded in the postcentral gyrus, and the probability of discharge is lower than for postcentral neurones.5. A further difference between neurones of the postcentral and precentral gyrus is the pronounced convergence from different nerves and also from different modalities (cutaneous and muscle afferents) in units of the precentral cortex in contrast to units of the postcentral cortex.6. The high thresholds, necessary to activate precentral neurones by muscle nerve stimulation, make it unlikely that group I muscle afferents are involved. This is, furthermore, indicated by the lack of responsiveness to intravenous injection of succinylcholine which was, however, effective for driving neurones of the specific projection area for group I afferents, area 3a. The present experiments are consistent with the view that sensitivity of precentral neurones to muscle stretch (described in previous studies) is due to activation of secondary muscle spindle endings and their ascending pathways.7. The original hypothesis of a load compensating ;pyramidal reflex' with an oligosynaptic afferent contribution from the spindle primaries can be discarded. The present findings indicate that there is a feed-back from secondary muscle spindle afferents which, by way of a more complex pathway, can modulate the firing frequency of neurones in the motor cortex.
Topics: Animals; Brain Mapping; Electric Stimulation; Evoked Potentials; Forearm; Hand; Haplorhini; Microelectrodes; Motor Cortex; Muscle Spindles; Muscles; Neural Conduction; Neurons, Afferent; Papio; Peripheral Nerves; Pyramidal Tracts; Skin; Succinylcholine
PubMed: 4265508
DOI: 10.1113/jphysiol.1973.sp010082 -
Journal of Neurology, Neurosurgery, and... Jun 1971An effort was made to corroborate earlier reports that the central nervous system rostral to a functionally complete transection of the human spinal cord remains...
An effort was made to corroborate earlier reports that the central nervous system rostral to a functionally complete transection of the human spinal cord remains responsive to noxious stimulation of sites below the level of the transection. Nine patients were studied who had sustained a functionally complete transection of the thoracic spinal cord between T5 and T11 spinal segments. Noxious electrocutaneous stimulation or intense pressure was applied to a lower extremity while electrodermal activity was recorded concurrently from contralateral palmar sites which were shown to be under normal suprasegmental control. While electrodermal responses were occasionally recorded in the post-stimulus intervals, there was no tendency for these responses to exceed the number or amplitude of responses recorded during stimulus-free control periods. These results were interpreted as suggesting that the few responses observed during the post-stimulus intervals were not evoked by stimulation of the lower extremities and were instead representative of spontaneous electrodermal activity or were related to uncontrolled auditory or visual stimuli accompanying lower extremity stimulation. Additional results highlighted the importance of controlling accessory auditory and visual cues occurring in conjunction with lower extremity stimuli. In some patients with a transection above the sympathetic outflow to the lower extremities, it was shown that electrodermal responses from the plantar aspect of each foot could be elicited reliably by lower extremity stimuli. These results confirmed previously reported evidence that the functionally isolated human spinal cord can reflexly mediate electrodermal responses.
Topics: Adolescent; Adult; Auditory Cortex; Electric Stimulation; Evoked Potentials; Female; Foot; Galvanic Skin Response; Hand; Humans; Lumbosacral Region; Male; Neck; Neurons, Afferent; Pressure; Reflex; Sensation; Spinal Cord Injuries; Spinal Nerves; Thorax; Visual Cortex
PubMed: 5571316
DOI: 10.1136/jnnp.34.3.281 -
Journal of the Experimental Analysis of... Jul 1965The effects on monitoring performance of a limited hold (LH) terminated by a bell or by electric shock and of periodic rest periods were investigated. The sensitivity of...
The effects on monitoring performance of a limited hold (LH) terminated by a bell or by electric shock and of periodic rest periods were investigated. The sensitivity of basal skin conductance to different monitoring conditions was also studied. Humans monitored a visual display in several 2-hr sessions under the Holland procedure. In each session, signals were programmed by one of the following three multiple schedules: a variable interval of 6 min (VI 6) and a VI 6 with a limited hold (LH) terminated by a bell; a VI 6 and a VI 6 LH terminated by electric shock; a VI 6 LH terminated by shock and a time-out (TO). The two components of each schedule alternated at 15-min intervals. The average observing response rate of eight subjects was lowest during the VI 6 periods, higher in periods when the LH was terminated by a bell, and highest when the LH was terminated by shock. Periodic TO periods did not appreciably increase the response rate under the VI 6 LH shock component. A differential level of palmar skin conductance under the two components of a schedule was present only under the mult VI 6 LH shock-TO.
Topics: Arousal; Attention; Conditioning, Operant; Electroshock; Galvanic Skin Response; Heart Rate; Humans; Learning; Male; Rest; Sound
PubMed: 14342025
DOI: 10.1901/jeab.1965.8-207