Metabolism of Skeletal Muscle Following Incomplete Ischemia

Abstract

The morphological changes in striated muscle following ischemia has been so far mainly studied with both optical and electron microscopes taking into consideration different parameters, such as duration, nature and course of the ischemia. 1, ~~ 3 The study of the metabolic changes in the above lesions was approached by measuring the lactate-pyruvate ratio, ATP, inorganic phosphorus, lactic acid and glycogen contents.4 Then a series of studies was reported on the alteration of metabolism in infarcted heart muscle following experimental occlusion of coronary vessels in dogs. The results of these studies have demonstrated that the first step in the reparative process is an enhancement in the synthesis of nuclear material associated with a marked increase in activity of the pentose phosphate shunt, and a sharp decrease in activity of mitochondrial (respiratory) and glycolytic enzymes.5Interest in the latter prompted our investigation on protein synthesis, oxygen uptake and anaerobic glycolysis in skeletal muscle following incomplete and &dquo;less&dquo; incomplete ischemia in rats as well as in rabbits. We reported elsewhere the results obtained using sural muscles ischemized incompletely by exclusion of the femoral and external iliac arteries. These results were consistent with an enhancement of C14-leucine incorporation into protein associated with an increase in activity in both oxygen and anaerobic glycolysis. The experimental conditions of incomplete ischemia were adopted to reproduce the main pathological features in human skeletal muscle following chronic vascular diseases.The results of the study on rabbit sural muscle ischemized at a &dquo;less&dquo; incomplete stage are reported in this present paper. We studied the metabolic responses to such an ischemia in relation to the pentose phosphate shunt, to glycolysis and respiration and measured the activity of eight main enzymes. Furthermore we checked the endoergonic processes by incorporating C14-leucine into protein. These data are in general agreement with those reported in infarcted heart muscle. MATERIALS AND METHODS Animals and surgeryExperiments were carried out on 16 young rabbits of both sexes, weighing around 2,500 gm, under local anaesthesia by subcutaneous injection of 1% novocaine. The femoral artery was excluded by ligature with a silk thread and at University of Otago Library on March 15, 2015 ang.sagepub.com Downloaded from

The pentose phosphate pathway in regenerating skeletal muscle

“…The activity of the pentose phosphate pathway in skeletal muscle is enhanced during embryogenesis (Beatty et al, 1966) and in a number of experimental situations, including denervation (Turner & Manchester, 1972;Ilyin et al, 1975;Robbins & Hall, 1976), ischaemia (Archangeli et al, 1973) and administration of Marcaine (bupivacaine, 1-n-butyl-DL-piperidine-2-carboxylic acid 2,6-dimethylanilide hydrochloride) (Rifenberick et al, 1974;Wagner et al, 1977b), a myotoxic local anaesthetic that causes acute degeneration of muscle fibres followed by rapid and complete regeneration (Benoit & Belt, 1970). At 1 day after local application of Marcaine, fibres of the rat extensor digitorum longus muscle undergo degeneration characterized morphologically by disappearance of the plasma membrane, alteration of mitochondria and the sarcotubular system, dissolution of myofibrils, and degeneration of myonuclei (Jirmanova & Thesleff, 1972).…”