On the nature of parabiosis intoxication: shock as the precipitating cause.

Spinal transection of one of a parabiotic pair of rats is immediately followed by a state indistinguishable in visual and hematologic characteristics from spontaneous "parabiosis intoxication." The transected rat develops erythremia, hyperhemoglobinemia, and an increased hematocrit count; whereas the twin concurrently shows anemia characterized by a decrease in hemoglobin, erythrocyte count, and hematocrit reading, and often also lipemia. These findings are ascribed to whole blood transfusion of one rat by the other followed by adjustments compensatory to the resulting distortion in the respective blood volumes. It is suggested that parabiosis intoxication is a manifestation of this same process and is not due, as has been contended, to an immune response.