Human skeletal muscle metabolism and morphology after temporary incomplete ischaemia.

Incomplete ischaemia was caused by clamping the aorta during reconstructive vascular surgery. After restoration of the blood flow extensive metabolic and morphological changes in the muscle tissue were observed. The adenylate (ATP + ADP + AMP) and the creatine (PCr + Cr) pools declined 30-40% and the energy charge of the adenine nucleotides dropped significantly. The metabolic pool changes were closely related to the changes in the lactate/pyruvate ratios. Morphological signs of membrane disturbances, such as fibre oedema and swelling of mitochondria, were seen in many muscle fibres 30 min after declamping. 5 days postoperatively, a number of mitochondrial abnormalities were observed and fibre regeneration was seen in places. The relative number of Type 2 fibres and the width of the capillary lumen were both related to the decrease of the metabolic parameters. Thus, the metabolic state and the fine structure of the incompletely ischaemic muscle were closely related to each other. The amount of Type 2 fibres seemed to be of special importance for the patho-physiological events in intermittently ischaemic muscle fibres.