ON THE VASO-CONSTRICTIVE ACTION OF SERUM ON THE CORONARY VESSELS OF THE MAMMALIAN

Cushny and Gunn (1) recently showed that when the isolated heart of a rabbit has been perfused with Ringer’s solution, the addition of serum or plasma to the Ringer reduces the flow through the coronary vessels, and in consequence of this marked changes follow in the cardiac contractions. These changes occur even when the animal’s own serum is employed. They ascribed this action not to any new substances having been formed in the serum, but to the vessels having been altered in their reaction through the previous perfusion of the Ringer’s solution. Others have supposed that new vaso-constrictor substances, not present in the blood, are formed in serum and cause the constriction of vessels through which they are perfused (Handovsky and Pick (2)). I have attempted to determine how far the effects observed by Cushny and Gunn may be obtained with other proteins and colloids and also to determine which constituents of the serum are responsible for the vaso-constriction in the coronary arteries. I have perfused the hearts of cats and rabbits by the same method as was described by Cushny and Gunn. The heart was first perfused with Ringer’s solution for 15-20 minutes, and then the solution to be examined was substituted at the same pres-sure and temperature; the fluid was oxygenated by a current of oxygen throughout the experiment. The results of my experiments are shown in the tables given below, in which the rate of flow is indicated by the number of at