The purpose was to determine if physiological characteristics of skeletal muscles of dogs and cats are related to their histochemical and biochemical characteristics. Maximum oxygen conumption (VO2max) and blood flow (Q) at VO2max were determined for in situ muscles of dogs and cats. Compared to cat muscles, dog muscles per unit mass had higher succinate oxidase activities, VO2max's, and Q's at VO2max's. There are positive relationships between Q at VO2 max and VO2max and between VO2max and succinate oxidase activity. The higher VO2max's and succinate oxidase activities of dog muscles are consistent with the presence in these muscles of only slow-twitch fatigue-resistant fibers and fast-twitch fatigue-resistant fibers, whereas up to 50% of the fibers found in cat muscles are fast-twitch fatiguable. Capillary-to-fiber ratios are 2.40to 2.97 for dog muscles compared to 2.17 to 2.84 for cat muscles. Thus the 2- to 3-fold higher Q at VO2max for dog muscles compared to cat muscles is not due to a greater number of capillaries.
ASJC Scopus subject areas
- Cell Biology