ABSTRACT
Patients suffering from Intermittent Claudication (IC) experience repeated periods of muscle contraction with low blood flow, throughout the day and this may contribute to the hypothesized skeletal muscle abnormalities. Our aim was to generate this basic physiological data, determining the “normal” response of healthy skeletal muscle tissue utilizing a canine gracilis model (n = 9), the muscle was stimulated to contract (5 Hz) for the 10 min periods (separated by 10 min rest) under low blood flow conditions (80 percent reduced), followed by 1 hr recovery and then a fourth period of 10 min stimulation. During the first period of contraction, adenosine triphosphate (ATP) was reduced by ~30 percent. During this period there was also a 10 fold increase in muscle lactate concentration and a substantial increase in muscle lactate and ammonia efflux. Subsequently, lactate efflux was similar during the first three periods, while ammonia efflux was reduced by the third period. Following the 1 hr recovery, muscle lactate and phosphocreatine concentrations had returned to resting values, while muscle ATP) remained 20 percent lower. During the fourth contraction period, no ammonia efflux or change in muscle ATP content occurred. Despite such contrasting metabolic responses, muscle tension and oxygen consumption were identical during all contraction periods from 310 min.
