Microneurographic studies of the mechanisms of sympathetic nerve responses to static exercise in humans.

The purpose of this study was to determine the contribution of muscle afferents and central command in regulating sympathetic nerve activity during static exercise in humans. In 20 healthy subjects, we recorded heart rate, arterial pressure, and efferent sympathetic nerve activity in the leg during arm exercise. Microelectrodes were inserted percutaneously into a fascicle of the peroneal nerve to measure sympathetic discharge to muscle. Measurements were obtained in nine subjects during sustained handgrip (30% maximal voluntary contraction) followed by relaxation or by arrested circulation of the forearm. Heart rate and arterial pressure increased during the first and second minutes of handgrip. Muscle sympathetic nerve activity increased from 261 +/- 46 to 504 +/- 97 units (mean +/- SE; units = burst frequency X amplitude; P less than 0.05) during the second minute of handgrip. During forearm ischemia following handgrip, heart rate returned promptly to control, whereas arterial pressure and muscle sympathetic nerve activity (631 +/- 115 units) remained elevated. In contrast, muscle sympathetic nerve activity returned toward control during relaxation without arrested circulation. These data indicate that muscle sympathetic nerve activity is increased by stimulation of chemically sensitive muscle afferents. To determine the influence of central command on muscle sympathetic nerve activity, we compared responses during an involuntary and a voluntary biceps contraction, each at 20% maximal voluntary contraction. Both maneuvers raised arterial pressure, but heart rate increased only during voluntary contraction. More importantly, muscle sympathetic nerve activity rose during involuntary contraction, but fell during voluntary effort.(ABSTRACT TRUNCATED AT 250 WORDS)

[1]  S. Walgenbach,et al.  Role of arterial and cardiopulmonary mechanoreceptors in the regulation of arterial pressure during rest and exercise in conscious dogs. , 1984, Mayo Clinic proceedings.

[2]  B. Wallin,et al.  Discharge patterns of sympathetic neurons supplying skeletal muscle and skin in man and cat. , 1983, Journal of the autonomic nervous system.

[3]  D E Donald,et al.  Maintained ability of carotid baroreflex to regulate arterial pressure during exercise. , 1981, The American journal of physiology.

[4]  F. Abboud,et al.  Modulation of the somatic reflex by carotid baroreceptors and by cardiopulmonary afferents in animals and in humans. , 1981, Circulation research.

[5]  L. Rowell,et al.  Cardiovascular responses to muscle ischemia in humans. , 1981, Circulation research.

[6]  J. T. Shepherd,et al.  Different behavior of the resistance vessels of the human calf and forearm during contralateral isometric exercise, mental stress, and abnormal respiratory movements. , 1981, Circulation research.

[7]  J. Mitchell,et al.  Response of arterial blood pressure to static exercise in relation to muscle mass, force development, and electromyographic activity. , 1981, Circulation research.

[8]  A. Vallbo,et al.  Somatosensory, proprioceptive, and sympathetic activity in human peripheral nerves. , 1979, Physiological reviews.

[9]  L. Rowell,et al.  Cardiovascular responses to muscle ischemia in man--dependency on muscle mass. , 1978, Journal of applied physiology: respiratory, environmental and exercise physiology.

[10]  W. J. Russell,et al.  Lack of effect of isometric handgrip exercise on the responses of the carotid sinus baroreceptor reflex in man. , 1978, Clinical science and molecular medicine.

[11]  U. Tibes,et al.  Reflex inputs to the cardiovascular and respiratory centers from dynamically working canine muscles. Some evidence for involvement of group III or IV nerve fibers. , 1977, Circulation research.

[12]  L. Rowell,et al.  Human cardiovascular and respiratory responses to graded muscle ischemia. , 1976, Journal of applied physiology.

[13]  L. Kaijser,et al.  Effect of regional alpha‐ and beta‐adrenergic blockade on blood flow in the resting forearm during contralateral isometric handgrip. , 1976, The Journal of physiology.

[14]  D. McCloskey,et al.  Muscular reflex stimuli to the cardiovascular system during isometric contractions of muscle groups of different mass. , 1975, The Journal of physiology.

[15]  K. Sagawa,et al.  Modulation of carotid sinus baroreceptor reflex by sciatic nerve stimulation. , 1975, American Journal of Physiology.

[16]  A P Hollander,et al.  Cardiac acceleration in man elicited by a muscle-heart reflex. , 1975, Journal of applied physiology.

[17]  E. Knutsson,et al.  Blood flow in resting (contralateral) arm and leg during isometric contraction , 1974, The Journal of physiology.

[18]  D. McCloskey,et al.  Absence of appreciable cardiovascular and respiratory responses to muscle vibration. , 1972, Journal of applied physiology.

[19]  D. McCloskey,et al.  Cardiovascular and respiratory responses to changes in central command during isometric exercise at constant muscle tension , 1972, The Journal of physiology.

[20]  D. McCloskey,et al.  Reflex cardiovascular and respiratory responses originating in exercising muscle , 1972, The Journal of physiology.

[21]  K. Hagbarth,et al.  Manoeuvres affecting sympathetic outflow in human skin nerves. , 1972, Acta physiologica Scandinavica.

[22]  S M Hilton,et al.  The reflex nature of the pressor response to muscular exercise , 1971, The Journal of physiology.

[23]  U. Freyschuss.  Cardiovascular adjustment to somatomotor activation. The elicitation of increments in heart rate, aortic pressure and venomotor tone with the initiation of muscle contraction. , 1970, Acta physiologica Scandinavica. Supplementum.

[24]  P. W. Humphreys,et al.  THE CIRCULATIORY EFFECTS OF SUSTAINED VOLUNTARY MUSCLE CONTRACTION. , 1964, Clinical science.

[25]  K. Donald,et al.  THE EFFECT OF VASCULAR OCCLUSION ON THE PRESSOR RESPONSE TO STATIC MUSCULAR WORK. , 1964, Clinical science.

[26]  V. C. Abrahams,et al.  The role of active muscle vasodilatation in the alerting stage of the defence reaction , 1964, The Journal of physiology.

[27]  E. Asmussen,et al.  EXPERIMENTS ON NERVOUS FACTORS CONTROLLING RESPIRATION AND CIRCULATION DURING EXERCISE EMPLOYING BLOCKING OF THE BLOOD FLOW. , 1964, Acta physiologica Scandinavica.

[28]  P. Korner.  Reflex regulation of post-exercise blood pressure. , 1952, The Australian journal of experimental biology and medical science.

[29]  B. Folkow,et al.  Activation of sympathetic vasodilator nerves to the skeletal muscles in the cat by hypothalamic stimulation. , 1951, Acta physiologica Scandinavica.

[30]  F. Smirk,et al.  Observations in man upon a blood pressure raising reflex arising from the voluntary muscles , 1937, The Journal of physiology.

[31]  A Krogh,et al.  The regulation of respiration and circulation during the initial stages of muscular work , 1913, The Journal of physiology.