Cyclooxygenase products sensitize group III and IV muscle afferents to dynamic exercise

Adreani, Christine M., Janeen M. Hill, and Marc P. Kaufman.Responses of group III and IV muscle afferents to dynamic exercise. J. Appl. Physiol. 82(6): 1811–1817, 1997.—Tetanic contraction of hindlimb skeletal muscle, induced by electrical stimulation of either ventral roots or peripheral nerves, is well known to activate group III and IV afferents. Nevertheless, the effect of dynamic exercise on the discharge of these thin fiber afferents is unknown. To shed some light on this question, we recorded in decerebrate cats the discharge of 24 group III and 10 group IV afferents while the mesencephalic locomotor region (MLR) was stimulated electrically. Each of the 34 afferents had their receptive fields in the triceps surae muscles. Stimulation of the MLR for 1 min caused the triceps surae muscles to contract rhythmically, an effect induced by an α-motoneuron discharge pattern and recruitment order almost identical to that occurring during dynamic exercise. Eighteen of the 24 group III and 8 of the 10 group IV muscle afferents were stimulated by MLR stimulation. The oxygen consumption of the dynamically exercising triceps surae muscles was increased by 2.5-fold over their resting levels. We conclude that low levels of dynamic exercise stimulate group III and IV muscle afferents.

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Cyclooxygenase blockade attenuates responses of group III and IV muscle afferents to dynamic exercise in cats

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.01274.2005 ◽

2006 ◽

Vol 290 (6) ◽

pp. H2239-H2246 ◽

Cited By ~ 41

Author(s):

Shawn G. Hayes ◽

Angela E. Kindig ◽

Marc P. Kaufman

Keyword(s):

Muscle Afferents ◽

Group Iv ◽

Dynamic Exercise ◽

Triceps Surae ◽

Afferent Activity ◽

Mesencephalic Locomotor Region ◽

Thin Fiber ◽

Group Iii ◽

Triceps Surae Muscles ◽

Stimulation Of

Cyclooxygenase products accumulate in statically contracting muscles to stimulate group III and IV afferents. The role played by these products in stimulating thin fiber muscle afferents during dynamic exercise is unknown. Therefore, in decerebrated cats, we recorded the responses of 17 group III and 12 group IV triceps surae muscle afferents to dynamic exercise, evoked by stimulation of the mesencephalic locomotor region. Each afferent was tested while the muscles were freely perfused and while the circulation to the muscles was occluded. The increases in group III and IV afferent activity during dynamic exercise while the circulation to the muscles was occluded were greater than those during exercise while the muscles were freely perfused ( P < 0.01). Indomethacin (5 mg/kg iv), a cyclooxygenase blocker, reduced the responses to dynamic exercise of the group III afferents by 42% when the circulation to the triceps surae muscles was occluded ( P < 0.001) and by 29% when the circulation was not occluded ( P = 0.004). Likewise, indomethacin reduced the responses to dynamic exercise of group IV afferents by 34% when the circulation was occluded ( P < 0.001) and by 18% when the circulation was not occluded ( P = 0.026). Before indomethacin, the activity of the group IV, but not group III, afferents was significantly higher during postexercise circulatory occlusion than during rest ( P < 0.05). After indomethacin, however, group IV activity during postexercise circulatory occlusion was not significantly different from group IV activity during rest. Our data suggest that cyclooxygenase products play a role both in sensitizing group III and IV afferents during exercise and in stimulating group IV afferents during postexercise circulatory occlusion.

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Dynamic exercise stimulates group III muscle afferents

Journal of Neurophysiology ◽

10.1152/jn.1994.71.2.753 ◽

1994 ◽

Vol 71 (2) ◽

pp. 753-760 ◽

Cited By ~ 55

Author(s):

J. G. Pickar ◽

J. M. Hill ◽

M. P. Kaufman

Keyword(s):

Receptive Field ◽

Receptive Fields ◽

Muscle Afferents ◽

Dynamic Exercise ◽

Triceps Surae ◽

Step Cycle ◽

Group Iii ◽

Afferent Fibers ◽

Triceps Surae Muscles ◽

Flexor Digitorum

1. In decerebrate cats, we investigated the responses of group III muscle afferents to dynamic exercise. The cats performed low intensity dynamic exercise on a treadmill. Group III afferent activity from the dynamically exercising triceps surae muscles was recorded from L7-S1 dorsal root filaments. 2. Single-unit recordings were obtained from 15 group III afferent fibers whose receptive fields were in the triceps surae muscles and from one group III afferent whose receptive field was in the flexor digitorum longus muscle. Conduction velocities for the 16 group III afferents ranged from 3.0 to 27.9 m/s (15.6 +/- 1.9 m/s, mean +/- SE). 3. Ten of 16 group III muscle afferents were stimulated by dynamic exercise. Of the 10, 7 were strongly responsive and 3 were mildly responsive to dynamic exercise. Each of the 10 afferents displayed at least some activity that was synchronized to the contraction phase of the step cycle. The mean developed tensions for strongly responsive afferents, mildly responsive afferents, and afferents that did not respond were 0.8 +/- 0.3, 1.3 +/- 0.5, and 0.7 +/- 0.3 Kg, respectively (P > 0.05). Thus differences in the responsiveness of the afferents to exercise were not attributable to differences in developed tensions. 4. The group III afferents that were strongly responsive to dynamic exercise were also mechanically sensitive. Each strongly responsive afferent (n = 7) was stimulated by nonnoxious pressure applied to its receptive field. Most strongly responsive afferents (n = 5) were stimulated by stretch of the triceps surae muscles.(ABSTRACT TRUNCATED AT 250 WORDS)

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Central alterations of neuromuscular function and feedback from group III-IV muscle afferents following exhaustive high-intensity one-leg dynamic exercise

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00280.2014 ◽

2015 ◽

Vol 308 (12) ◽

pp. R1008-R1020 ◽

Cited By ~ 21

Author(s):

Benjamin Pageaux ◽

Luca Angius ◽

James G. Hopker ◽

Romuald Lepers ◽

Samuele M. Marcora

Keyword(s):

High Intensity ◽

Muscle Pain ◽

Evoked Potential ◽

Motor Evoked Potential ◽

Neuromuscular Function ◽

Muscle Afferents ◽

Dynamic Exercise ◽

Afferent Feedback ◽

Group Iii ◽

Leg Muscle

The aims of this investigation were to describe the central alterations of neuromuscular function induced by exhaustive high-intensity one-leg dynamic exercise (OLDE, study 1) and to indirectly quantify feedback from group III-IV muscle afferents via muscle occlusion (MO, study 2) in healthy adult male humans. We hypothesized that these central alterations and their recovery are associated with changes in afferent feedback. Both studies consisted of two time-to-exhaustion tests at 85% peak power output. In study 1, voluntary activation level (VAL), M-wave, cervicomedullary motor evoked potential (CMEP), motor evoked potential (MEP), and MEP cortical silent period (CSP) of the knee extensor muscles were measured. In study 2, mean arterial pressure (MAP) and leg muscle pain were measured during MO. Measurements were performed preexercise, at exhaustion, and after 3 min recovery. Compared with preexercise values, VAL was lower at exhaustion (−13 ± 13%, P < 0.05) and after 3 min of recovery (−6 ± 6%, P = 0.05). CMEParea/Marea was lower at exhaustion (−38 ± 13%, P < 0.01) and recovered after 3 min. MEParea/Marea was higher at exhaustion (+25 ± 27%, P < 0.01) and after 3 min of recovery (+17 ± 20%, P < 0.01). CSP was higher (+19 ± 9%, P < 0.01) only at exhaustion and recovered after 3 min. Markers of afferent feedback (MAP and leg muscle pain during MO) were significantly higher only at exhaustion. These findings suggest that the alterations in spinal excitability and CSP induced by high-intensity OLDE are associated with an increase in afferent feedback at exhaustion, whereas central fatigue does not fully recover even when significant afferent feedback is no longer present.

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Group III/IV muscle afferents are important for the pressor response to dynamic exercise in healthy humans (1165.9)

The FASEB Journal ◽

10.1096/fasebj.28.1_supplement.1165.9 ◽

2014 ◽

Vol 28 (S1) ◽

Author(s):

Lauro Vianna ◽

Thales Barbosa ◽

Igor Fernandes ◽

Nisval Magalhães ◽

Ismar Cavalcanti ◽

...

Keyword(s):

Pressor Response ◽

Muscle Afferents ◽

Dynamic Exercise ◽

Group Iii ◽

Healthy Humans

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Effect of arterial occlusion on responses of group III and IV afferents to dynamic exercise

Journal of Applied Physiology ◽

10.1152/jappl.1998.84.6.1827 ◽

1998 ◽

Vol 84 (6) ◽

pp. 1827-1833 ◽

Cited By ~ 83

Author(s):

Christine M. Adreani ◽

Marc P. Kaufman

Keyword(s):

Arterial Occlusion ◽

Muscle Afferents ◽

Group Iv ◽

Dynamic Exercise ◽

Hydrogen Ion ◽

Group Iii ◽

Low Level ◽

Exercise Induced ◽

Decerebrate Cats ◽

Stimulation Of

Our laboratory has shown previously that a low level of dynamic exercise induced by electrical stimulation of the mesencephalic locomotor region (MLR) stimulated group III and IV muscle afferents in decerebrate unanesthetized cats (C. M. Adreani, J. M. Hill, and M. P. Kaufman. J. Appl. Physiol. 83: 1811–1817, 1997). In the present study, we have extended these findings by examining the effect of occluding the arterial supply to the dynamically exercising muscles on the afferents’ responses to MLR stimulation. In decerebrate cats, we found that arterial occlusion increased the responsiveness to a low level of dynamic exercise in 44% of the group III and 47% of the group IV afferents tested. Occlusion, compared with the freely perfused state, did not increase the concentrations of either hydrogen ion or lactate ion in the venous effluent from the exercising muscles. We conclude that arterial occlusion caused some unspecified substance to accumulate in the working muscles to increase the sensitivity of equal percentages of group III and IV afferents to dynamic exercise.

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