Dynamics of PO 2 and VO 2 in resting and contracting rat spinotrapezius muscle
This study examined changes in interstitial PO , which allowed calculation of VO during periods of rest, muscle contraction and recovery using an rat spinotrapezius muscle preparation. The PO was measured using phosphorescence quenching microscopy and the muscle VO was calculated as the rate of O di...
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Published in | Frontiers in physiology Vol. 14; p. 1172834 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
Switzerland
2023
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Subjects | |
Online Access | Get full text |
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Summary: | This study examined changes in interstitial PO
, which allowed calculation of VO
during periods of rest, muscle contraction and recovery using an
rat spinotrapezius muscle preparation. The PO
was measured using phosphorescence quenching microscopy and the muscle VO
was calculated as the rate of O
disappearance during brief periods of muscle compression to stop blood flow with a supra-systolic pressure. The PO
and VO
measurements were made during "5 s compression and 15 s recovery" (CR) cycles. With all three stimulation frequencies, 1, 2 and 4 Hz, the fall in interstitial PO
and rise in VO
from resting values occurred within the first 20 s of contraction. The PO
during contraction became lower as stimulation frequency increased from 1 to 4 Hz. VO
was higher at 2 Hz than at 1 Hz contraction. With cessation of stimulation, PO
began increasing exponentially towards baseline values. After 1 and 2 Hz contraction, the fall in muscle VO
was delayed by one CR cycle and then exponentially decreased towards resting values. After 4 Hz stimulation, VO
increased for 2 cycles and then decreased. The post-contraction transients of PO
and VO
were not synchronous and had different time constants. With further analysis two distinct functional responses were identified across all stimulation frequencies having PO
during contraction above or below 30 mmHg. The corresponding VO
responses were different - for "high" PO
, muscle VO
reached high levels, while for the "low" PO
data set muscle VO
remained low. Recovery patterns were similar to those described above. In summary, local microscopic PO
and VO
were measured in resting and contracting muscle
and the post-contraction transients of PO
and VO
were all much slower than the onset transients. |
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ISSN: | 1664-042X 1664-042X |