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Local regulation of oxygen supply in rat skeletal muscle in vivo: variations in hemodynamic response
Author(s) -
Milkovich Stephanie Lynn,
MacKie Meaghan,
Goldman Daniel,
Ellis Christopher G
Publication year - 2007
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.21.5.a481-d
Subject(s) - hematocrit , hemodynamics , chemistry , capillary action , blood flow , microcirculation , anatomy , haemodynamic response , skeletal muscle , oxygenation , biophysics , oxygen , medicine , endocrinology , heart rate , biology , blood pressure , physics , thermodynamics , organic chemistry
To test the hypothesis that red blood cells (RBC) regulate oxygen (O 2 ) supply within organs we used a gas exchange chamber in the stage of an inverted microscope to alter the O 2 environment at a muscle surface (rat extensor digitorum longus) using computer controlled gas flowmeters. With temperature and CO 2 levels constant, the microvascular response to sine oscillations in chamber O 2 levels (3 cycles, period 120 seconds) were determined by measuring hemodynamic parameters: RBC velocity ( v ), capillary hematocrit ( Hc ), RBC supply rate ( SR ) and RBC O 2 saturation levels in capillaries near the muscle surface using our functional microvascular imaging system. Sine oscillations in chamber O 2 caused oscillations in capillary hemodynamics which were 180 degrees out of phase with the chamber O 2 . To determine if there was a significant regulatory response, the r 2 correlation between the measured oscillation in chamber O 2 and in capillary v , SR and Hc were calculated for 13 capillaries (7 rats). There were significant correlations with SR , v and Hc in 11, 10 and 9 capillaries respectively. In six capillaries the regulatory response occurred as a change in both v and Hc , but in another six capillaries only one parameter changed ( v – 3, Hc – 3). The variable response is likely due to the relative magnitude of flow distributions at bifurcations deeper in the muscle caused by regulation of arteriolar blood flow to the surface capillaries.