Blockade of the pressor response to muscle ischemia by sensory nerve block in man

Freund, Peter R.; Rowell, L. B.; Murphy, Terence M.; Hobbs, S. F.; Butler, Sam

doi:10.1152/ajpheart.1979.237.4.h433

Cited by 39 publications

(48 citation statements)

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“…Our findings are consistent with previous hemodynamic observations, which suggest that the neurocirculatory adjustments to mild dynamic exercise are not dependent upon muscle chemoreflexes (29,30). In humans, elimination of muscle afferent input with selective sensory nerve block did not attenuate the increases in arterial pressure and HR during mild, nonischemic 04 mg/kg i.v.).…”

Section: Exercise Interventions Series Isupporting

confidence: 92%

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Differential control of heart rate and sympathetic nerve activity during dynamic exercise. Insight from intraneural recordings in humans.

Victor¹,

Seals²,

Mark³

1987

J. Clin. Invest.

219

150

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We used microelectrode recordings of muscle sympathetic nerve activity (MSNA) from the peroneal nerve in the leg during arm exercise in conscious humans to test the concept that central command and muscle afferent reflexes produce mass sympathetic discharge at the onset of exercise. Nonischemic rhythmic handgrip and mild arm cycling produced graded increases in heart rate and arterial pressure but did not increase MSNA, whereas ischemic handgrip and moderate arm cycling dramatically increased MSNA. There was a slow onset and offset of the MSNA responses, which suggested metaboreceptor mediation. When forearm ischemia was continued after ischemic handgrip, MSNA remained elevated (muscle chemoreflex stimulation) but heart rate returned to control (elimination of central command). The major new conclusions are that: (a) the onset of dynamic exercise does not produce mass, uniform sympathetic discharge in humans, and (b) muscle chemoreflexes and central command appear to produce differential effects on sympathetic and parasympathetic responses.

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Section: Exercise Interventions Series Isupporting

confidence: 92%

“…exercise (29). In dogs, moderate decreases in muscle perfusion that would potentiate muscle chemoreflexes did not accentuate the arterial pressure and HR responses to mild dynamic exercise (30).…”

Section: Exercise Interventions Series Imentioning

confidence: 84%

Differential control of heart rate and sympathetic nerve activity during dynamic exercise. Insight from intraneural recordings in humans.

Victor¹,

Seals²,

Mark³

1987

J. Clin. Invest.

219

150

View full text Add to dashboard Cite

show abstract

“…While the arterial occlusion cuff did maintain mean arterial pressure at a slightly higher level than the 'no cuff' treatment, epidural anaesthesia failed to significantly reduce this response as it does during dynamic exercise (Freund et al 1979;Kjaer et al 1988). Given the low level at which the arterial cuff maintains blood pressure after static exercise, it may not be surprising that the epidural anaesthesia failed to significantly effect an additional diminution.…”

Section: Discussionmentioning

confidence: 98%

“…Furthermore, reversible postexercise ischaemia of dynamically exercising muscle maintains mean arterial pressure, heart rate, and ventilation (Alam & Smirk, 1937, 1938 which are attenuated by epidural anaesthesia (Freund, Rowell, Murphy, Hobbs & Butler, 1979;Kjaer et al 1988).…”

mentioning

confidence: 99%

Epidural anaesthesia and cardiovascular responses to static exercise in man.

Mitchell

Reeves

Rogers

et al. 1989

The Journal of Physiology

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SUMMARY1. In human subjects, sustained static contractions of the knee extensors were performed in one leg with the same absolute (10% of the initial maximal voluntary contraction) and relative (30 % of the maximal voluntary contraction immediately prior to the static exercise) intensities before and during epidural anaesthesia. Epidural anaesthesia reduced strength to 62 + 8 % of the control value and partially blocked sensory input from the working muscles. During contractions performed with the same relative force, the increases in mean arterial pressure and heart rate were greater during control contractions than during epidural anaesthesia. During contractions at the same absolute force, there was no significant difference in magnitude of cardiovascular responses between control contractions and contractions performed during epidural anaesthesia.2. The metabolic role in the exercise pressor reflex was assessed by applying an arterial leg cuff 10 s before cessation of exercise and through the following 3 min of recovery. Although mean arterial pressure and heart rate decreased immediately after cessation of exercise, application of the arterial occlusion cuff resulted in higher post-exercise mean arterial pressure and heart rate values. Control and epidural mean arterial pressures during arterial occlusion were not significantly different.3. The results of this study suggest that the reflex neural mechanism rather than the intended effort (central command) is important in determining the blood pressure and heart rate responses to static exercise in man. That is, when epidural anaesthesia diminishes sensory feedback and produces muscular weakness, central command does not determine the cardiovascular response. This conclusion, however, is opposite to that derived from experiments with partial neuromuscular blockade which demonstrated the importance of central command in determining the cardiovascular response to static exercise (Leonard, Mitchell, Mizuno, Rube, Saltin & Secher, 1985). Taken together, these two studies are complementary and support the concept that both central and reflex neural mechanisms play roles in regulating arterial blood pressure and heart rate during static exercise in man.

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“…Muscle metaboreceptors were isolated from other important reflex systems by the maneuver called "posthandgrip circulatory arrest," in which a blood pressure cuff placed proximally on the exercising arm is inflated to suprasystolic levels at the conclusion of handgrip exercise. 14,[17][18][19][20] This occludes arm Renal circulation during sustained handgrip (SHG) exercise (10% MVC). A, Peak RCVR during SHG exercise (10% MVC) was significantly greater in heart failure patients than in normal controls (37Ϯ2 vs 24Ϯ1 U, Pϭ0.0001).…”

Section: Discussionmentioning

confidence: 99%

Exaggerated Renal Vasoconstriction During Exercise in Heart Failure Patients

et al. 2000

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Background —During static exercise in normal healthy humans, reflex renal cortical vasoconstriction occurs. Muscle metaboreceptors contribute importantly to this reflex renal vasoconstriction. In patients with heart failure, in whom renal vascular tone is already increased at rest, it is unknown whether there is further reflex renal vasoconstriction during exercise. Methods and Results —Thirty-nine heart failure patients (NYHA functional class III and IV) and 38 age-matched control subjects (controls) were studied. Renal blood flow was measured by dynamic positron emission tomography. Graded handgrip exercise and posthandgrip ischemic arrest were used to clarify the reflex mechanisms involved. During sustained handgrip (30% maximum voluntary contraction), peak renal vasoconstriction was significantly increased in heart failure patients compared with controls (70±13 versus 42±1 U, P =0.02). Renal vasoconstriction returned to baseline in normal humans by 2 to 5 minutes but remained significantly increased in heart failure patients at 2 to 5 minutes and had returned to baseline at 20 minutes. In contrast, during posthandgrip circulatory arrest, which isolates muscle metaboreceptors, peak renal vasoconstriction was not greater in heart failure patients than in normal controls. In fact, the increase in renal vasoconstriction was blunted in heart failure patients compared with controls (20±5 versus 30±2 U, P =0.05). Conclusions —During sustained handgrip exercise in heart failure, both the magnitude and duration of reflex renal vasoconstriction are exaggerated in heart failure patients compared with normal healthy humans. The contribution of the muscle metaboreceptors to reflex renal vasoconstriction is blunted in heart failure patients compared with normal controls.

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Blockade of the pressor response to muscle ischemia by sensory nerve block in man

Cited by 39 publications

References 0 publications

Differential control of heart rate and sympathetic nerve activity during dynamic exercise. Insight from intraneural recordings in humans.

Differential control of heart rate and sympathetic nerve activity during dynamic exercise. Insight from intraneural recordings in humans.

Epidural anaesthesia and cardiovascular responses to static exercise in man.

Exaggerated Renal Vasoconstriction During Exercise in Heart Failure Patients

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