Preservation of skeletal muscle hyperemic response to contraction with aging in female rats.

In a previous investigation (Irion et al., 1987), a significant age-related decline in skeletal muscle blood flow during intermittent tetanic contractions was observed in male Fischer 344 rats. This decline in the hyperemic response to muscle contraction was accompanied by an increased fatigability of skeletal muscle of senescent male rats. In the present investigation, anesthetized female adult and senescent Fischer 344 rats were instrumented for stimulation of the plantar flexor muscles in situ, and blood flow measurement by the tracer microsphere technique. After determination of optimum length and maximum tetanic force, muscles were stimulated to contract at the rate of 120 tetani/min. No significant differences could be observed between adult and senescent females in skeletal muscle fatigability or blood flow. The only significant differences observed between senescent and younger females were a decrease in splenic blood flow and an increase in body weight. In contrast to male rats of the same age, no impairment of skeletal muscle blood flow or change in fatigability could be detected in senescent female rats.