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Department of Clinical Physiology and Nuclear Medicine, Bispjeberg Hospital, DK-2400 Copenhagen NV; and The Copenhagen Muscle Research Centre, Department of Anesthesia, University of Copenhagen, DK-2100 Copenhagen Ø, Denmark
Received 3 January 1996; accepted in final form 6 June 1996.
Williamson, J. W., D. B. Friedman, J. H. Mitchell, N. H. Secher, and L. Friberg. Mechanisms regulating regional cerebral activation during dynamic handgrip in humans. J. Appl.
Physiol. 81(5): 1884-1890, 1996.
Dynamic hand
movement increases regional cerebral blood flow (rCBF) of the
contralateral motor sensory cortex (MS1). This increase is eliminated
by regional anesthesia of the working arm, indicating the importance of
afferent neural input. The purpose of this study was to determine the
specific type of afferent input required for this cerebral activation. The rCBF was measured at +5.0 and +9.0 cm above the orbitomeatal (OM)
plane in 13 subjects during 1) rest;
2) dynamic left-hand contractions;
3) postcontraction ischemia
(metaboreceptor afferents); and 4)
biceps brachii tendon vibration (muscle spindles). The rCBF increased
only during dynamic hand contraction; contralateral MS1 (OM +9) by 15%
to 64 ± 8.6 ml · 100 g
1 · min
1
(P < 0.05); supplementary motor area
(OM +9) by 11% to 69 ± 9.8 ml · 100 g
1 · min
1
(P < 0.05); and there were also
bilateral increases at MS2 (OM +5) [by 16% to 64 ± 8.6 ml · 100 g
1 · min
1
(P < 0.05)]. These findings
suggest that the rCBF increase during dynamic hand contraction does not
require neural input from muscle spindles or metabolically sensitive
nerve fibers, although the involvement of mechanoreceptors (group III
or Ib) cannot be excluded.
single-photon-emission computerized tomography; 133Xe inhalation; muscle ischemia; tendon vibration; exercise
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