Peripheral factors influencing expression of pressor reflex evoked by muscular contraction

Iwamoto, Gary A.; Botterman, B. R.

doi:10.1152/jappl.1985.58.5.1676

Cited by 45 publications

(36 citation statements)

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“…Although the difference in findings between the present report and the study of Stebbins et al (37) may be due to species effects, it should be noted that the relative mass (i.e., as a percentage of total body muscle mass) of the triceps surae muscle in the cat is much larger than the relative mass of the wrist muscles and fingers flexors of the human. Previous work (19) suggests that the muscle mass is linked to the magnitude of the pressor response. Although stretch of forelimb cat muscles evoked significantly greater cardiovascular responses than those noted during hindlimb muscle stretch (12), it is unknown whether stretch of very small muscle mass in the cat could evoke significant autonomic responses.…”

Section: Discussionmentioning

confidence: 99%

Effects of muscle metabolites on responses of muscle sympathetic nerve activity to mechanoreceptor(s) stimulation in healthy humans

Cui

Mascarenhas

Moradkhan

et al. 2008

American Journal of Physiology-Regulatory, Integrative and Comp

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Based on animal studies, it has been speculated that muscle metabolites sensitize muscle mechanoreceptors and increase mechanoreceptor-mediated muscle sympathetic nerve activity (MSNA). However, this hypothesis has not been directly tested in humans. In this study, we tested the hypothesis that in healthy individuals passive stretch of forearm muscles would evoke significant increases in mean MSNA when muscle metabolite concentrations were increased. In 12 young healthy subjects, MSNA, ECG, and blood pressure were recorded. Subjects performed static fatiguing isometric handgrip at 30% maximum voluntary contraction followed by 4 min of postexercise muscle ischemia (PEMI). After 2 min of PEMI, wrist extension (i.e., wrist dorsiflexion) was performed. The static stretch protocol was also performed during 1) a freely perfused condition, 2) ischemia alone, and 3) PEMI after nonfatiguing exercise. Finally, repetitive short bouts of wrist extension were also performed under freely perfused conditions. This last paradigm evoked transient increases in MSNA but had no significant effect on mean MSNA over the whole protocol. During the PEMI after fatiguing handgrip, static stretch induced significant increases in MSNA (552 +/- 74 to 673 +/- 90 U/min, P < 0.01) and mean blood pressure (102 +/- 2 to 106 +/- 2 mmHg, P < 0.001). Static stretch performed under the other three conditions had no significant effects on mean MSNA and blood pressure. The present data verified that in healthy humans mechanoreceptor(s) stimulation evokes significant increases in mean MSNA and blood pressure when muscle metabolite concentrations are increased above a certain threshold.

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Section: Discussionmentioning

confidence: 99%

Effects of muscle metabolites on responses of muscle sympathetic nerve activity to mechanoreceptor(s) stimulation in healthy humans

Cui

Mascarenhas

Moradkhan

et al. 2008

American Journal of Physiology-Regulatory, Integrative and Comp

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“…Certainly, Some pathophysiological conditions are associated with alterations in group III/IV afferent sensitivity or their elicited reflexes (Murphy et al, 2011). In addition, the role of these fibers can vary across skeletal muscle fiber type and muscle group (Iwamoto and Botterman, 1985, Martin et al, 2006), and thus the picture is not actually so simple. Indeed, the increase in afferent feedback achieved by the increase in active muscle mass in our study from KE to BIKE was likely not directly proportional to the change in muscle mass.…”

Section: Discussionmentioning

confidence: 99%

“…A relationship between the magnitude of afferent feedback and muscle mass has long been established (Freund et al, 1978, Iwamoto and Botterman, 1985). Freund et al (Freund et al, 1978) demonstrated that post-bicycle exercise occlusion of blood flow to both legs maintained mean arterial pressure at a higher level than occlusion of one leg alone.…”

Section: Introductionmentioning

confidence: 99%

Muscle mass and peripheral fatigue: a potential role for afferent feedback?

et al. 2012

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AIM The voluntary termination of exercise has been hypothesized to occur at a sensory tolerance limit which is significantly determined by feedback from group III and IV muscle afferents, and is associated with a specific level of peripheral quadriceps fatigue during whole body cycling. Therefore, the purpose of this study was to reduce the amount of muscle mass engaged during dynamic leg exercise to constrain the source of muscle afferent feedback to the central nervous system (CNS), and examine the effect on peripheral quadriceps fatigue. METHOD Eight young males performed exhaustive large (cycling – BIKE) and small (knee extensor – KE) muscle mass dynamic exercise at 85% of the modality-specific maximal workload. Pre- vs post-exercise maximal voluntary contractions (MVC) and supramaximal magnetic femoral nerve stimulation (Qtw,pot) were used to quantify peripheral quadriceps fatigue. RESULT Significant quadriceps fatigue was evident following both exercise trials; however, the exercise-induced changes in MVC (−28±1% vs −16±2%) and Qtw,pot (−53±2% vs −34±2%) were far greater following KE compared to BIKE exercise, respectively. The greater degree of quadriceps fatigue following KE exercise was in proportion to the greater exercise time (9.1±0.4 vs. 6.3±0.5 minutes, p<0.05), suggestive of a similar rate of peripheral fatigue development. CONCLUSION These data suggest that when the source of skeletal muscle afferent feedback is confined to a small muscle mass, the CNS tolerates a greater magnitude of peripheral fatigue, and likely a greater intramuscular metabolic disturbance. An important implication of this finding is that the adoption of small muscle mass exercise may facilitate greater exercise-induced muscular adaptation.

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“…Specifically, it has been suggested that muscles composed of slow twitch fibers do not generate a pressor response when stimulated to contract (26). However, this issue remains unsettled since others have shown in a cat model that the slow twitch soleus muscle will generate a pressor response if made to contract maximally (27).…”

Section: Experimental Protocolsmentioning

confidence: 99%

Hydrogen ion concentration is not the sole determinant of muscle metaboreceptor responses in humans.

Sinoway¹,

Rea²,

Mosher³

et al. 1992

J. Clin. Invest.

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We examined the effects of exercise conditioning on muscle sympathetic nerve activity (MSNA) during handgrip and posthandgrip circulatory arrest (PHG-CA). Two conditioning stimuli were studied: forearm dominance and bodybuilding. Static handgrip at 30% maximal voluntary contraction followed by PHG-CA led to a rise in MSNA smaller in dominant than in nondominant forearms (99% vs. 222%; P < 0.02) and in body builders than in normal volunteers (28% vs. 244%; P < 0.01). Separate 31P NMR experiments showed no effect of dominance on forearm pH but a pH in bodybuilders higher (6.88) than in normal volunteers (6.79; P < 0.02) during PHG-CA.Our second goal was to determine if factors besides attenuated [H'J contribute to this conditioning effect. If differences in MSNA during exercise were noted at the same pH, then other mechanisms must contribute to the training effect. We measured MSNA during ischemic fatiguing handgrip. No dominance or bodybuilding effect on pH was noted. However, we noted increases in MSNA smaller in dominant than nondominant forearms (212% vs. 322%; P < 0.02) and in bodybuilders than in normal volunteers (161% vs. 334%; P < 0.01). In summary, MSNA responses were less during exercise of conditioned limbs. Factors aside from a lessening of muscle acidosis contribute to this effect. (J. Clin. Invest. 1992.

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Peripheral factors influencing expression of pressor reflex evoked by muscular contraction

Cited by 45 publications

References 0 publications

Effects of muscle metabolites on responses of muscle sympathetic nerve activity to mechanoreceptor(s) stimulation in healthy humans

Effects of muscle metabolites on responses of muscle sympathetic nerve activity to mechanoreceptor(s) stimulation in healthy humans

Muscle mass and peripheral fatigue: a potential role for afferent feedback?

Hydrogen ion concentration is not the sole determinant of muscle metaboreceptor responses in humans.

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