THE EFFECTS OF MULTIPLE INJECTIONS OF BACTERIAL ENDOTOXIN ON BLOOD COAGULATION IN THE TOADFISH, OPSANUS TAU

¹ Department of Aquaculture Science and Pathology, University of Rhode Island, Kingston, Rhode Island 02881; the Departments of Laboratory Medicine and Medicine, University of California School of Medicine, San Francisco, California 94143; and the Marine Biological Laboratory, Woods Hole, Massachusetts 02543

The effects of multiple injections of bacterial endotoxin on blood coagulation in the toadfish, Opsanus tau, were studied. Preparations of endotoxin from Escherichia coli, Aeromonas hydrophila, or Vibrio harveyi (strain 392) were utilized. Three injections of endotoxin were administered at either 6 or 12 h intervals.

Although there was a slight decrease in plasma fibrinogen concentration following the administration of endotoxin, levels did not significantly differ from normal controls. Endotoxins from E. coli and A. hydrophila initially shortened the prothrombin time (PT), but subsequently the PT returned to normal. In contrast, the partial thromboplastin time (PTT) was not shortened following the administration of bacterial endotoxin. There was no detectable effect on the plasma recalcification time. There were no significant differences between the red and white blood cell levels of control fish and fish that had received endotoxin. Endotoxins from A. hydrophila and V. harveyi reduced the survival of recipient toadfish, whereas E. coli did not increase mortality during the period of observation. Although both control and experimental fish demonstrated increased hematopoietic activity in the kidney, only O. tau that had received endotoxin demonstrated marked necrosis of interstitial cells.

Our data indicate that multiple injections of bacterial endotoxin into the toadfish result in alterations of blood coagulation compatible with activation of the blood coagulation mechanism. However, striking evidence of a consumptive coagulopathy, as is observed in mammals following multiple injections of bacterial endotoxin, was not observed. Interestingly, toadfish tolerated doses of endotoxin markedly greater than those sufficient to produce not only alterations of blood coagulation but also rapid death in many mammalian species.