ISSN:
1440-1681
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
1. To clarify the limiting factors for peak V̇o2 (V̇o2peak)〉 we measured muscle venous Po2 (Pvo2) and V̇o2, peak under various O2 delivery conditions (arterial O2 concentration X flow) via the alteration of blood flow and haematocrit (Hct) in anaesthetized dog gastrocnemius muscle (n= 11) stimulated by 1 Hz isometrically and tetanically.2. Two levels of flow (high and moderate) were maintained by using a pump (ISO and 100 mL/min per 100 g, respectively). Haematocrit was adjusted to 45 and 30% by isovolaemic haemodilution with dextran (MW 40 000).3. The decrease in Hct induced a 31% decrease in O2 delivery (P〈0.05), a 9–12% decrease in Pvo2, a 23% decrease in V̇o2, peak(P〈0.05) and a 12–14% increase in O2 extraction (V̇o2/O2delivery) at both flow levels. The decrease in flow induced a 24–25% decrease in O2 delivery (P〈0.05), a 15–17% decrease in Pvo2 (P〈0.05), a 9% decrease in V̇o2,peak (P〈0.05) and a 19–22% increase in O2 extraction (P〈0.05) at both Hct levels.4. The results suggest that the limiting factor of V̇o2peak, unrelated to O2 diffusion limitation (i.e. the change in the heterogeneity of V̇o2 to O2 delivery ratio among capillaries), due to lowering Hct may be different from that due to lowering blood flow in maximally contracting muscle.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1440-1681.1997.tb01805.x
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