Skeletal muscle chemoreflex and pH<sub>i</sub>in exercise ventilatory control

Oelberg, David A.; Evans, Allison B.; Hrovat, Mirko I.; Pappagianopoulos, Paul P.; Patz, Samuel; Systrom, David M.

doi:10.1152/jappl.1998.84.2.676

Cited by 30 publications

(22 citation statements)

References 50 publications

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“…In experimental and human physiological studies, several putative metabolic and humoral triggers have been investigated. 8 -16 In particular, chemical products of muscle metabolism, such as increased production of lactic acid, 7 H ϩ , 8,24 or increased blood release of K ϩ , 19,25 have been investigated. Alterations in peripheral vessel conductance have also been suggested.…”

Section: Introductionmentioning

confidence: 99%

Skeletal Muscle Reflex in Heart Failure Patients

et al. 2003

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Background-An important role of the increased stimulation of skeletal muscle ergoreceptors (intramuscular afferents sensitive to products of muscle work) in the genesis of symptoms of exertion intolerance in chronic heart failure (CHF) has been proposed. With the use of selective infusions and dietary manipulation methods, we sought to identify the role of H ϩ , K ϩ , lactate, and peripheral hemodynamics on ergoreflex overactivation. Methods and Results-Ten stable CHF patients (aged 67.9Ϯ2.5 years, peak oxygen uptake 16.3Ϯ1.2 mL · kg Ϫ1 · min Ϫ1 ) and 10 age-matched and sex-matched healthy subjects were studied. The ergoreflex contribution to ventilation was assessed by post-handgrip regional circulatory occlusion (PH-RCO) and computed as the difference in ventilation between PH-RCO and a control run without PH-RCO. This test was performed on 6 separate occasions. On each occasion a different chemical was infused (insulin, sodium nitroprusside, sodium bicarbonate, dopamine, or saline) or a 36-hour glucose-free diet was undertaken before the test. During all stages of the protocol, the local muscular blood effluent concentrations of H ϩ , K ϩ , glucose, and lactate were assessed. An ergoreflex effect on the ventilatory response was seen in patients (versus control subjects) during the saline infusions (6.7Ϯ2.3 L/min versus Ϫ0.1Ϯ0. Key Words: heart failure Ⅲ muscles Ⅲ nervous system, autonomic Ⅲ reflex Ⅲ ventilation T he ergoreflex consists of a brain stem autonomic and ventilatory response activated by signals from the periphery, such as free nerve ending group III and IV muscle afferents. 1 It has been hypothesized that muscle metabolic abnormalities and/or circulatory insufficiencies of chronic heart failure (CHF) cause local overproduction and accumulation of muscle metabolic products, which trigger the ergoreceptors. 2,3 Our lab and others have confirmed this hypothesis by demonstrating that the muscle ergoreflexes of the forearm muscles, 4 the small muscles used in dorsiflexing the foot, 5 and the muscles of the quadriceps 6 cause an enhanced ventilatory response in CHF. An overactivation of the muscle ergoreflex during exercise has been shown to be closely related to patient symptoms and to the ventilatory response to exercise, and a role of this reflex in contributing to exercise intolerance in CHF has been proposed. 4 The triggering mediators responsible for the ergoreflex stimulation and their involvement in the abnormal exercise responses in CHF remain to be established. Different metabolic and humoral products have been studied in animals [7][8][9][10][11][12] and in humans, 13-15 but few investigators have investigated factors specifically involved in the ergoreflex overactivation of CHF patients. 16,17 One (or more) of these mediators may be involved as a link between alterations in muscle metabolism and/or hemodynamics present in CHF and the ventilatory response to exercise, via activation of muscle reflex.We have investigated the role of the putative triggers in muscle ergoreflex activation. The id...

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Section: Introductionmentioning

confidence: 99%

Skeletal Muscle Reflex in Heart Failure Patients

et al. 2003

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“…Similarly, exercise hyperpnoea has been shown to be reduced during a selective occlusion of the arterial circulation to exercising muscles (without concomitant venous obstruction) in anaesthetised dogs (Huszczuk et al 1993) or in patients with severe peripheral vascular disease (Haouzi et al 1997). In contrast, partial obstruction of the circulation by cuff inflation at pressures below systolic BP, or by an increase in local pressure (Eiken, 1987;Oelberg et al 1998) during muscle contractions appears to stimulate l & in humans.…”

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confidence: 99%

Control of breathing and muscle perfusion in humans

Haouzi

Chenuel

Chalon

2001

Experimental Physiology

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Very brief and intense exercise triggers a biphasic metabolic and respiratory response with a second phase that occurs after the cessation of the muscular activity. The effects on minute ventilation (VE) produced by manipulation of the peripheral circulation in metabolically active muscles could thus be studied without the confounding effects of painful contractions. The second phase of breath-by-breath ft and pulmonary gas exchange responses to a brief change in work rate (400 W for 12 s) were studied in six healthy male subjects on four occasions (24 tests). An upper thigh cuff inflation was randomly applied either above or below the systolic blood pressure (200 or 90 Torr, respectively) for 90 s just after the cessation of the contractions prior to the delayed rise in pulmonary gas exchange (eight tests in each subject). Total occlusion produced a significant reduction in the delayed rise in T & (-29 ? 3 %) which normally occurred 20-25 s after the cessation of the contractions. In contrast, cuff inflation at a level predominantly impeding venous return while partially maintaining the arterial supply reduced the rise in pulmonary gas exchange in similar proportion to that during total obstruction but with a slight but not significant reduction in ventilation (-9 f 5%). ft during partial occlusion was if anything higher than in control tests with similar oxygen uptake (280 W), despite a higher blood pressure (BP) during occlusion (+7 Torr). It is concluded that the factors resulting from a reduction in venous return or from the involvement of the arterial baroreflex are not responsible for the changes in ft produced by the obstruction of the circulation to and from metabolically active muscles. It is proposed that factors related to the level of the perfusion pressure in hyperaemic muscles, possibly located at the venular end of the microcirculation, could account for the changes in J& observed.

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“…Alternatively, chemoreceptors and/or mechanoreceptors in the working muscles have been proposed to link the ventilatory control Mense and Stahnke, 1983;Kaufman and Rybicki, 1987;Kaufman and Forster, 1996;Oelberg et al, 1998;Haouzi, 1999Haouzi, , 2006. In the present study, since the magnitude, pattern, and duration of the load imposed by the two protocols were the same, it is likely that there was no difference in mechanical and chemical stimuli to peripheral afferents (e.g.…”

Section: Discussionmentioning

confidence: 73%

“…Furthermore, Pa CO 2 , which is involved in arterial chemoreceptors and perhaps group Ⅳ neural afferents (Oelberg et al, 1998), was not different between the two protocols.…”

Section: Discussionmentioning

confidence: 78%

Effects of awareness of change in load on ventilatory response during moderate exercise

Yunoki

Matsuura

Arimitsu

et al. 2009

Respiratory Physiology & Neurobiology

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This study was designed to determine whether awareness of change in load alters ventilatory response during moderate exercise. Subjects performed two incremental exercise protocols on a cycle ergometer. The load was increased from 1.0 to 1.5 kp in steps of 0.1 kp every 3 min. Subjects were provided true information about the load in the control protocol and untrue information that the load would remain constant in the deception protocol. Slope of ventilation against CO 2 output was significantly lower in the deception protocol than control protocol. Integrated EMG (iEMG) and ratings of perceived exertion (RPE) were similar between the two protocols, but awareness of change in load was significantly attenuated by the deception protocol.However, there was no temporal coincidence between awareness and actual change in load. These results suggest that ventilatory response during moderate exercise depends not so much on RPE but mainly on awareness or attention that is closely connected to information detection.

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Skeletal muscle chemoreflex and pH_iin exercise ventilatory control

Cited by 30 publications

References 50 publications

Skeletal Muscle Reflex in Heart Failure Patients

Skeletal Muscle Reflex in Heart Failure Patients

Control of breathing and muscle perfusion in humans

Effects of awareness of change in load on ventilatory response during moderate exercise

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Skeletal muscle chemoreflex and pHiin exercise ventilatory control

Cited by 30 publications

References 50 publications

Skeletal Muscle Reflex in Heart Failure Patients

Skeletal Muscle Reflex in Heart Failure Patients

Control of breathing and muscle perfusion in humans

Effects of awareness of change in load on ventilatory response during moderate exercise

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Skeletal muscle chemoreflex and pH_iin exercise ventilatory control