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

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.

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

[2]  C. L. Stebbins,et al.  Reflex cardiovascular and ventilatory responses to increasing H+ activity in cat hindlimb muscle. , 1989, Journal of applied physiology.

[3]  S. Mense,et al.  Responses in muscle afferent fibres of slow conduction velocity to contractions and ischaemia in the cat. , 1983, The Journal of physiology.

[4]  J. Hill,et al.  Dynamic exercise stimulates group III muscle afferents. , 1994, Journal of neurophysiology.

[5]  J. Longhurst,et al.  Sensitization of group III muscle afferents to static contraction by arachidonic acid. , 1990, Journal of applied physiology.

[6]  M. Kaufman,et al.  Discharge Properties of Group III and IV Muscle Afferents: Their Responses to Mechanical and Metabolic Stimuli , 1987, Circulation research.

[7]  J. Mitchell,et al.  The exercise pressor reflex: its cardiovascular effects, afferent mechanisms, and central pathways. , 1983, Annual review of physiology.

[8]  J. Kiley,et al.  Stimulation by central command of locomotion, respiration and circulation during exercise. , 1985, Respiration physiology.

[9]  B R Botterman,et al.  Activation of type-identified motor units during centrally evoked contractions in the cat medial gastrocnemius muscle. I. Motor-unit recruitment. , 1996, Journal of neurophysiology.

[10]  J. Hill,et al.  Cyclooxygenase blockade attenuates responses of group IV muscle afferents to static contraction. , 1990, The American journal of physiology.

[11]  Michael J. O'Donovan,et al.  Discharge patterns of hindlimb motoneurons during normal cat locomotion. , 1981, Science.

[12]  S. Mense,et al.  Bradykinin‐induced modulation of the response behaviour of different types of feline group III and IV muscle receptors. , 1988, The Journal of physiology.

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

[14]  A. Mark,et al.  Hydrogen ion concentration is not the sole determinant of muscle metaboreceptor responses in humans. , 1992, The Journal of clinical investigation.

[15]  C. Adreani,et al.  Responses of group III and IV muscle afferents to dynamic exercise. , 1997, Journal of applied physiology.

[16]  B R Botterman,et al.  Activation of type-identified motor units during centrally evoked contractions in the cat medial gastrocnemius muscle. II. Motoneuron firing-rate modulation. , 1996, Journal of neurophysiology.

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

[18]  J. E. McKenzie,et al.  Resting blood flow and oxygen consumption in soleus and gracilis muscles of cats. , 1980, The American journal of physiology.

[19]  N. Vøllestad,et al.  Motor Unit Recruitment , 1987 .

[20]  J. Mitchell,et al.  Effects of static muscular contraction on impulse activity of groups III and IV afferents in cats. , 1983, Journal of applied physiology: respiratory, environmental and exercise physiology.

[21]  T. Waldrop,et al.  Effect of ischemia on responses of group III and IV afferents to contraction. , 1984, Journal of applied physiology: respiratory, environmental and exercise physiology.

[22]  E. Bockman.  Blood flow and oxygen consumption in active soleus and gracilis muscles in cats. , 1983, American Journal of Physiology.

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