INOEBRIOTSEN, R. and S. LERAAND. Dilatation of a medium-sizcd artery immediately after local changes of blood pressure and flow as meaJured by ultrasonic terhnique. Acta physiol. scand. 1970. 79. 552-558. The effect of changes in blood pressure and flow on the calibre of the medium-sized artery has been studied in model experiments with an a-v fistula on the femoral vessels in dogs, On opening of the fistula a large local fall of blood pressure proximal to the fistula and an increase in flow up to 1000 74has been found. With the use of an ultrasonic technique for measurement of arterial diameter-by which it was possible to measure changes in the diameter in the order of 0.001 mm-we found an immediate increase, in the order of 10 %, in the diameter of the femoral artery on the opening of the a-v fistula. This increase remained as long as the fistula was patent. The results were identical in 5 dogs.The effect on the diameter of clamping the artery for some time, with consequent removal of the clamp, was examined in 5 dogs. Removal of the clamp itself resulted in only a small and temporary increase in the diameter of the artery. I t is concluded that the dilatation of the artery on opening of the fistula must be connected to the sudden increase in flow.

Since guinea pig bone marrow and lymph gland cultivated for five days with goat blood generate substances that are hemolytic for goat red blood corpuscles, it can be concluded that tissues living outside of the organism react against an antigen by the production of an antibody.

The results in the group in which there was interagglutination differ in no striking way from those obtained in the group in which there was no interagglutination. It may be concluded, therefore, that the presence of isoagglutinins is of no importance for the final results of the homoplastic transplantation of arteries. From the conflicting evidence of the survival of muscular fibers in one case and their disappearance in many other cases, it may be concluded further that between animals of the same species there are unknown biological differences that prevent, in most instances, the survival of homoplastic transplanted arteries, although a survival does occur in some cases.

No abstract