Non-standard O(2) consumption-temperature curves during rest and isometric exercise in human skeletal muscle.
The present work was aimed at measuring intramuscular oxygen consumption (O(2)) as a function of temperature (T), in human forearm, during rest and aerobic isometric exercise (4% of the maximal voluntary contraction, MVC). Based upon results from in vitro experiments performed on isolated mitochondria of animal species, it was hypothesised that, during isometric exercise, the O(2)-T curve should display a maximum for some 'optimal' T. Intramuscular T and measurements were performed using a combined deep body temperature/near infrared probe during muscle cooling. At rest, O(2) increased non-linearly and monotonically as a function of T (n=8). O(2) increased approximately 2 times when going from 26 to 36 degrees C. A log(O(2))-T plot or a log(O(2))-1/T did not linearise the data. During isometric contraction, O(2) values at 26.8+/-0.6, 28.6+/-0.9, 31.9+/-0.9 and 35.9+/-0.9 degrees C were 3.04+/-1.26, 7.60+/-1.64, 4.43+/-1.95, and 6.64+/-1.37 micromol 100 g(-1) min(-1), respectively (n=6). The O(2) value at 28.6 degrees C was significantly higher (P<0.05) than that at 26.8 and 31.9 degrees C. The 'sudden' O(2) change at 28.6 degrees C is compatible with the phenomenon observed at the mitochondrial level.
Binzoni
Tiziano
T
Department of Radiology, University of Geneva, Geneva, Switzerland. tiziano.binzoni@medecine.unige.ch
Ngo
Loan
L
Hiltbrand
Emile
E
Springett
Roger
R
Delpy
David
D
D000818:Animals; D004175:Diptera / Q000378:metabolism; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008931:Mitochondria, Muscle / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism*; D010101:Oxygen Consumption; D012146:Rest / Q000502:physiology*; D013055:Spectrophotometry, Infrared; D013696:Temperature; D013997:Time Factors