Abstract
A series of investigations are in progress in this laboratory dealing with the changes brought about in the blood plasma by the injection of drugs and also by various pathological conditions.
Since some method of preventing the coagulation of the blood plasma has to be employed, it became essential to study the effects of the commonly used anticoagulants on the appearance of plasma under the ultramicroscope. In previous communications 1 , 2 oxalated rabbit's plasma had been used.
Samples of frog's blood (Rana catasbiana) were collected into oiled tubes without the use of any anticoagulant, centrifuged, the plasma pipetted off and diluted 1:5 with specially prepared, particle free, 0.75% physiological saline solution, and examined under the ultramicroscope. Similar samples were received into heparin (1/3 mgm. per cc.), potassium oxalate (2 mgm. per cc.) and sodium citrate (2.5 mgm. per cc.). The blood was also made non-coagulable by injection of heparin into the dorsal lymph sac 45 minutes previous to bleeding. The appearance of the various samples of plasma was then compared under the ultramicroscope with the normal plasma obtained without the use of any anticoagulant. Quantitative readings were also made of the relative refractiveness of the various plasmas, employing the photometer described by Hirschfelder and Wright. 3
The use of heparin either in vivo or in vitro produced only small changes in the appearance of the plasma. With potassium oxalate the particles appeared smaller, greater in number, and of increased refractiveness. Sodium citrate brought about a very marked reduction in the apparent size of the particles, with corresponding increase in the number of particles visible, and increase in refractiveness. This change in the colloidal equilibrium of the plasma proteins with addition of sodium citrate may be of importance in connection with the use of sodium citrate as an anticoagulant in blood transfusions.
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