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Measurements of Blood Flow, Tissue Oxygen Tension, and Oxygen Consumption in Rat Skeletal Muscle during Recovery from Bouts of Brief, Transient Ischemia
Author(s) -
Dodhy Sami C,
Golub Aleksander S,
Pittman Roland N
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.946.13
Subject(s) - ischemia , blood flow , oxygen , laser doppler velocimetry , reactive hyperemia , chemistry , oxygenation , oxygen tension , skeletal muscle , anesthesia , microcirculation , anatomy , medicine , organic chemistry
In resting muscle, blood flow is regulated to meet the demand for O 2 by the respiring tissue. A locally induced ischemia/reperfusion protocol was utilized to investigate the effects of transient ischemia (5, 15, 30, and 60 s duration) in rat skeletal muscle. The results will be utilized in a model that relates blood flow, interstitial oxygenation, and oxygen consumption. We anticipate that this study will aid in furthering our understanding of the local regulation of blood flow and tissue oxygenation. 29 spinotrapezius muscles from male Sprague‐Dawley rats were surgically exteriorized for intravital microscopy. Interstitial PO 2 (P ISF O 2 ) and arteriolar PO 2 (P a O 2 ) measurements were made using phosphorescence quenching microscopy (PQM). Red cell velocity was measured using Optical Doppler velocimetry and used to calculate blood flow (Q). Oxygen consumption (VO 2 ) was measured with a quasi‐continuous, flash‐synchronized, rapidly pressurizing airbag system to both initiate ischemia and sample the rate of change in oxygen tension (dPO 2 /dt). The average baseline value of arteriolar blood flow was measured as 5.8±0.8 μl/min; as expected, reactive hyperemia was observed during the recovery from ischemia. Flow recovery (dQ/dt) was fastest [3.88±0.64 (μl·min −1 )/s] after 60 seconds of ischemia. Average baseline P ISF O 2 was 62±4 mmHg; P ISF O 2 decreased to 75%, 34%, 10% and 2% of baseline following 5, 15, 30 and 60 s of ischemia, respectively. Up to 30 s of ischemia, the rate of recovery of P ISF O 2 steadily increased as the ischemic duration increased; however, it dropped off following 60 seconds of ischemia. The rate of recovery of P ISF O 2 was fastest (4.2±0.7 mmHg/s) following 30 seconds of ischemia. Average baseline VO 2 was 120±19 nl O 2 /cm 3 ·s and it increased above baseline during the early part of the recovery period. As is consistent with our current understanding, the time course of recovery of P ISF O 2 represents a balance between oxygen delivery, proportional to the local arteriolar tissue perfusion, and local oxygen consumption. When the ischemic duration increased, the interstitial oxygen tension decreased. An assumption was made in the modeling process that the arteriolar oxygen tension did not change during the course of each trial. Further investigation of both intravascular and perivascular P a O 2 using the PQM system and the same ischemia/reperfusion protocol will highlight any differences in the supply of oxygen to the interstitium versus what was already present at baseline. Support or Funding Information Supported by AHA Award #14GRNT20380551