Inhibition by rutin of capillary injury by alpha-radiation in rats.

By JOHN Q. GRIFFITH, JR., M.D. AND JAMES F. Coucir, Pri.1). A CONVENIENT LABORATORY METHOI) for determining the activity of various substances in preserving or restoring the integrity of the capillary wall has long been desired. Methods that (lepen(1 upon the production of cutaneous petechiae by either negative or positive pressure are open to certain objections, afl(l results obtained by such technics are not generally accepted. A test of this kind is of special importance in investigating the so-called vitamin P action of the flavonoids. Other t.echnics have been employed : the “sparing” action on epinephrin,13 permeability of capillaries to dyes4 and l)re\’ention of irradiation injury.5’8 None of these has been universally accepted as definitely indicating a vitamin P action and some have been severely criticized.9 Ilecently the technic of Griffith, Anthony, Pendergrass and Perryman’#{176} has been a(Iapted to the determination of the protective action of rutin on the pentoneal capillaries. Radon ointment, a source of alpha radiation, is introduced into the penitoneal cavity of normal rats in quantities sufficient to provide 40 to 2J9 I.Lc. This ointment contains small quantities of radon gas in either lanolin or olive oil.41 Alpha part.icles comprise 90 per cent of the radiation ; the remainder consists of 1)eta particles and gamma rays. After ten days, increased capillary fragility may be demonstrated in the peritoneal circulation by the following procedure: 1 nder general anesthesia the penitoneal cavity is opened by a long mid-line longitudinal incision, care being taken to exert no traction on the peritoneum. The abdominal wall is carefully folded back until an artery and vein are thisclosed. Then, under a good light., t.he peritoneum is grasped on each side of the vessels and stretched between the fingers so that the lumen of the vein is ohhiterated but the artery can still be seen pulsating. The tension is maintained for two minutes, after which it is relaxed. The peritoneal area supplied by the vessels is carefully inspect.ed and, if t.he fragility is increased, one or more petechiae will appear distal to the point of venous obstruction, usually entirely separat.e from any visible vessel. In a positive case, six or eight such hemorrhages usually occur. If desired, the process can be repeated in the same animal, using other vessels. No pet.echial hemorrhages occur in the normal animal. When rutin was given, it was always given for the first time ten to thirty