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Muscle blood flow and distribution determine maximal VO2 of contracting muscle

STAINSBY WENDELL N.; BRECHUE, WILLIAM F.; AMEREDES, BILL T.
Medicine & Science in Sports & Exercise: January 1995
BASIC SCIENCES/REGULATORY PHYSIOLOGY: Symposium: Mechanisms Which Control JOURNAL/mespex/04.02/00005768-199501000-00022/ENTITY_OV0312/v/2017-07-20T222434Z/r/image-pngO2 Near JOURNAL/mespex/04.02/00005768-199501000-00022/ENTITY_OV0312/v/2017-07-20T222434Z/r/image-pngO2max: PDF Only

ABSTRACT

During repetitive contractions, the VO2 of the dog gastrocnemius-plantaris muscle rose with the contraction frequency up to a maximal value and then decreased as contraction frequency was increased further. PVO2 was constant over most of the contraction frequency range. Reducing perfusion pressure/blood flow reduced JOURNAL/mespex/04.02/00005768-199501000-00022/ENTITY_OV0312/v/2017-07-20T222434Z/r/image-pngO2max), with a constant PVO2. During these maneuvers the diffusion conductance, DCO2 (JOURNAL/mespex/04.02/00005768-199501000-00022/ENTITY_OV0312/v/2017-07-20T222434Z/r/image-pngO2/PVO2), changed with JOURNAL/mespex/04.02/00005768-199501000-00022/ENTITY_OV0312/v/2017-07-20T222434Z/r/image-pngO2. Raising the perfusion pressure/flow with a pump increased JOURNAL/mespex/04.02/00005768-199501000-00022/ENTITY_OV0312/v/2017-07-20T222434Z/r/image-pngO2 with a small rise in PVO2 so that DCO2 also increased. Removing tension from the muscle-between contractions elevated JOURNAL/mespex/04.02/00005768-199501000-00022/ENTITY_OV0312/v/2017-07-20T222434Z/r/image-pngO2 and DCO2 without a change in perfusion pressure. Hypoxemia decreased JOURNAL/mespex/04.02/00005768-199501000-00022/ENTITY_OV0312/v/2017-07-20T222434Z/r/image-pngO2 with a decrease in PVO2,; DCO2 remained constant. A three-compartment mathematical model, based on microsphere measurements of regional flow, was used to illustrate how regional flow variations may exist, and how they are poorly revealed in the mixed whole-muscle venous blood. The model shows JOURNAL/mespex/04.02/00005768-199501000-00022/ENTITY_OV0312/v/2017-07-20T222434Z/r/image-pngO2·g−1 strongly related to flow. As JOURNAL/mespex/04.02/00005768-199501000-00022/ENTITY_OV0312/v/2017-07-20T222434Z/r/image-pngO2·−1 increased as JOURNAL/mespex/04.02/00005768-199501000-00009/ENTITY_OV0422/v/2017-07-20T222434Z/r/image-png·g−1 Increased, extraction decreased; and DCO2 increased.

©1995The American College of Sports Medicine