Abstract
If the lungs of a normal dog are perfused with Locke's solution, followed by Locke's solution containing 0.25 per cent. to 1 per cent. horse serum, no recognizable pulmonary reaction takes place. The rate of perfusion flow remains constant on changing from Locke's solution to the dilute serum. The lungs collapse normally on releasing the tracheal clamp. No frothy fluid escapes from the trachea.
If the lungs of a sensitized dog are similarly perfused, marked pulmonary reactions occur. These reactions are:
(a) A 75 per cent. reduction in the rate of perfusion flow. This reduction reaches its maximum by the end of two minutes, with slight tendency to recovery after the third minute.
(b) An increase in the size and consistency of the lungs, with non-collapse on release of the tracheal clamp.
(c) The escape of large amounts of fluid from the trachea on releasing this clamp. If the perfusion is now continued, fluid continues to pour out of the trachea almost as fast as it escapes from the efferent canula.
To our mind the increased capillary permeability thus dernonstrated is the most significant feature of these reactions. We believe that increased specific capillary permeability will ultimately be shown to be the dominant fundamental factor in protein sensitization, to which all other anaphylactic phenomena are secondary. This view is in accord with clinical evidence.
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