title: Effects of reduced O2 delivery with anemia, hypoxia, or ischemia on peak VO2 and force in skeletal muscle.
abstract: This investigation was designed to describe alterations in O2 uptake (VO2) and tension development in a contracting in situ gastrocnemious-plantaris muscle preparation during three conditions of reduced O2 delivery [arterial O2 concentration X blood flow (Q)]. The three conditions, hypoxemia (H), ischemia (I), and anemia (A), were matched for O2 delivery. A normoxic normal flow condition was also utilized for comparison. H was produced by respiring the animals with 9% O2 in N2; I was produced by lowering Q, and A was produced by hemodilution with 6% dextran. The stimulation pattern for the isometric tetanic contractions used was 1 train/s, and each train was 200 ms, 70 Hz, and 6 V. The muscle was maximally contracted during each of the experimental conditions, and the conditions were administered in random order. In each bout the contractions continued for 5 min with 30 min of rest between bouts. Samples of arterial and muscle venous blood were obtained during the last 30 s of each bout. VO2 during I (125 ml.kg-1.min-1) was less than during N (145 ml.kg-1.min-1; P < 0.05) and greater than during H or A (104 and 101 ml.kg-1.min-1, respectively; P < 0.05). Venous PO2 (PVO2) was significantly lower during H (17.1 Torr) compared with the other conditions; no differences existed between N, I, and A (26.8, 26.0, and 28.1 Torr, respectively). Tension development was reduced by the reduction of O2 delivery during I, H, and A compared with N. Tension developed among the reduced O2 delivery groups was not significantly different.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Exercise and Sport Sciences, University of Florida, Gainesville 32611.
authors.forename: S L
authors.initials: SL
authors.lastname: Dodd
authors.forename: S K
authors.initials: SK
authors.lastname: Powers
authors.forename: E
authors.initials: E
authors.lastname: Brooks
authors.forename: M P
authors.initials: MP
authors.lastname: Crawford
mesh_terms: D000740:Anemia / Q000503:physiopathology*; D000818:Animals; D004285:Dogs; D055590:Electromagnetic Phenomena; D000860:Hypoxia / Q000503:physiopathology*; D007511:Ischemia / Q000503:physiopathology*; D007537:Isometric Contraction / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology; D009132:Muscles / Q000098:blood supply* / Q000378:metabolism / Q000502:physiology; D010100:Oxygen / Q000097:blood / Q000494:pharmacology*; D010101:Oxygen Consumption / Q000502:physiology*; D012039:Regional Blood Flow
chemical_list: D010100:Oxygen