Abstract
1. Of the colloids examined, only serum and egg-white proved to possess the characteristic vaso-constrictor action on the coronary vessels, with the accompanying changes in the heart beat, while soluble starch, dextrin, glutin, arabin, agar-agar and peptone, either had no effect or in some cases dilated the coronary vessels.
2. The colloids of serum and egg-white are the constituents which possess this action, and these lose their efficiency when they have been precipitated by salts or alcohol; but the proteins which are not precipitated by boiling temperature (in feebly alkaline media) continue to act, and Hardy and Gardiner's pure proteins also preserve their action when prepared by acetoneether.
3. The effect of these proteins on the flow is very similar to that of dilute alkali; but when alkali is used, the change in the hydrogen ion concentration which is necessary to cause this action is far greater than that observed when serum is added to Ringer's solution. The action of serum on the coronary circulation and heart therefore cannot be explained by the serum changing the alkalinity of the perfusing fluid.
Footnotes
- Received October 1, 1915.
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