Discrepency Between Evidence and Theory of Myoglobin S02 in Work
Gayeski, Federspiel and Honig  showed that myoglobin Po2 during maximum electrically stimulated exercise in dog gracilis muscle fell as low as 1 torr, but usually was limited to 3–5 torr, and was remarkably uniform, suggesting that much of the diffusion gradient for 02 was between red cells and myocytes. Myoglobin is 50% saturated at about 4 torr, pH = 7, and has no Bohr effect. Its dissociation curve is a single exponential. In recent experiments Richardson et al. , using 1H MRS quantification of the quadriceps myoglobin.signal with one leg exercise in human volunteers, indicated that SMb02 fell with mild exercise (25% Vo2max) to about 50%, but remained at that level at four higher work levels (approaching Vo2max).
KeywordsDiffusion Gradient Bohr Effect Work Increase Capillary Recruitment Mild Exercise
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