Studies of Rickettsial Toxins

[摘要] A reproducible series of vascular reactions can be seen in vivo in the skin of mice injected with 4 LD50 of murine typhus toxin. Following toxin injection, there is an initial lag period of about half an hour during which the circulation appears normal; this is followed, in sequence, by slowing of the blood flow, constriction of the arterial channels and edema.Hemoconcentration and extravasation of fluids become detectable about 40 minutes after administration of toxin and both increase in intensity until the mouse dies in vascular collapse about an hour later.Evidence obtained in experiments employing high molecular weight tracer substances suggests that the plasma leakage during rickettsial toxemia occurred diffusely throughout most of the tissues of the animal.The pattern of the vascular reactions after toxin is very similar, except for the edema, to that occurring in mice in response to a decrease in blood volume produced by progressive hemorrhage.Increased vascular permeability with resultant loss of plasma is considered a basic physiologic abnormality in toxemic mice which leads to the recognizable chain of events that terminate in death. The means by which rickettsial toxin induces this increased permeability remains a matter of conjecture.

[学科分类] 生物科学（综合）