Summary:The catalytic aetivity of up to fifteen enzymes was investigated in the liver, heart, skeletal muscle, kidney (medulla, cortex), brain, hing, duodenum, spieen and pancreas from man and animals. Human specimens were obtained from autopsies and immediately post-mortem from dogs, rabbits, guinea pigs, rats and mice. The differences between our results and previous reports of considerably lower activities for structural enzymes (e. g. creatine kinase) and for enzymes partly of mitochondrial origin (e. g. glutamate dehydrogenase, aspartate aminotransferase, malate dehydrogenase), is attributed to our use of a detergent extraction technique. The superiority of the detergent technique with regard to enzyme yield is exemplified by a comparison of various methods of extraction in rat liver, heart and skeletal muscle. Use of standardized assays allows a qualitative inter-species comparison of results. The influence of autolysis on catalytic aetivity of human autopsies is considered of minor importance. Katalytische Enzymaktivitätskonzentration in Geweben von

From human and dog peripheral blood, thrombocytes (TRC), mononuclear cells (MNC), polymorphonuclear cells (PMNC), and red blood cells (RBC), were harvested after separation on a discontinuous Percoli gradient in a two-step centrifugation procedure, and 12 enzyme activities were determined in these highly purified cells. The enzyme activities measured are generally severalfold higher than previously reported, a fact which is attributed to the gentle and time-shortening isolation in Percoli, the cell disruption technique using detergent and the enzyme test conditions.

A technique is described which allows a fractionation of rabbit, guinea pig, rat and mouse blood cells using a discontinuous Percoli gradient. With only two steps of centrifugation a simultaneous isolation of thrombocytes, mononuclear cells, polymorphonuclear cells, and erythrocytes in nearly pure form is performed in a very short time, starting from only 1 ml of blood. In these morphologically almost homogeneous cell fractions the activities of 12 enzymes were determined. The enzyme pattern, which with respect to the number of enzymes, specific cell populations and species was not yet investigated to such an extent, revealed a manifold higher enzyme content in the few cases, in which comparative studies were made. This can be attributed mainly to the completeness of the cell disruption technique using a detergent and certainly also to the use of Percoli as a preferable gradient material.

Enzyme release from perfused rat heart was determined under various conditions of injury. In analogous experiments, intracellular cation concentrations were measured using ion-selective microelectrodes. Under appropriate conditions, the inhibition of mitochondrial and/or glycolytic ATP production led to a decrease in the release of enzymes. During ischaemia or the oxygen paradox, the sarcosolic Ca 2+ concentration was highly elevated; reperfusion or reoxygenation was followed by a drastic enzyme release. This was also found to be true under the conditions of an increased permeability brought about by a reduced extracellular Ca 2+ concentration of 0.1 mmol/1. The intracellular pH under all conditions of injury was only moderately decreased. The sarcosolic Na + concentration was markedly increased whereas the K + concentration was decreased. The critical Ca 2+ concentration of the sarcosol beyond which cell damage and enzyme release are inducible was assumed to be in the range between 10 and 32 μιηοΐ/ΐ. The driving force of the Na + /Ca 2+ exchange reaction of the sarcolemma is discussed in relation to recovery from hypoxic injury and the potential for avoiding cell damage.

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