The serum activity of creatine phosphokinase is elevated in clinical
and experimental tetanus due to an increased leakage into the blood of the isoenzyme
contained in skeletal muscle. This might be a simple effect of the increased
muscular activity characteristic of tetanus, but a direct effect of tetanus toxin on
the permeability of the muscle cell membrane cannot be excluded. Hyperbaric
oxygen treatment of rabbits suffering from severe tetanus produced by the intravenous
injection of toxin affected neither this increased enzymatic activity nor the
clinical course of the disease. Lactate dehydrogenase activity was consistently increased
in human patients and alpha-hydroxybutyrate dehydrogenase activity
temporarily. In rabbits, the activities of these enzymes increased in a roughly
proportional fashion, suggesting myocardial damage. Serum cholinesterase activity
was decreased in patients above 45 years of age. A satisfactory explanation of this
phenomenon cannot be given at present.