Role of Particulate Matter in Perfusion of Blood Vessels. ∗

A series of perfusion studies were made in which the capillary vessels of the frog's mesentery were kept under observation through the microscope. Striking differences were found between the circulation obtained with perfusates containing particulate matter and that obtained with similar solutions which were particle-free. Colloidal Ringer perfusates free of particulate matter did not fill all the vessels of the capillary bed, circulating only through the a-v capillaries. In a previous publication, 1 it was pointed out that the a-v capillaries represent direct continuations of the arterioles and serve as bridging channels to the venules. The dye T-1824 (Evans blue, Eastman Kodak Co.) has been used for blood volume studies because of its poor diffusibility. 2 When solutions containing Evans blue were used, the restriction of the color to the a-v capillaries stood out in contrast to the true capillaries which remained colorless. The addition of particulate matter, either as a fine suspension of carbon or of washed, rooster red cells, to the Ringer-gelatin or Ringer-acacia perfusates altered the restricted circulation within 30 to 45 seconds by distributing the solution throughout all of the capillaries.

During the early stages of the perfusion with particle-free Ringer-gelatin solutions, it was observed that the true capillaries were quickly emptied of their contained blood cells. This was peculiar since other observations had shown that the circulation of such perfusates was sharply restricted to the a-v vessels. By observing the vessels at the commencement of the per fusion, the blood cells in the true capillaries were seen to move simultaneously towards both the arterial and venous ends of the vessels and to be swept into the a-v circulation. This phenomenon appeared to be brought about by a suction effect arising from the rapid streaming of the perfusate past the true capillary orifices in the walls of the a-v channels.