Observations Indicating Absence of Glomerular Intermittence in Normal Dogs. ∗

Abstract

Khanolkar 1 and Hayman and Starr 2 have reported experiments on rabbits which they interpreted as showing that usually only a fraction of the renal glomeruli are open to circulating blood. The principle in both sets of experiments was essentially the same, the injection of hemoglobin or dye into the blood stream with subsequent examination of the kidneys to determine what fraction of the capsules or glomeruli contained the injected material. The percentage of glomeruli receiving the injected material varied in different experiments from 11 to 100.

The present paper reports findings on 12 kidneys of 8 normal dogs which are interpreted as evidence that all the glomeruli are normally open all the time. The renal arteries were exposed usually by flank incision, sometimes by midline laparotomy, under nembutal, 32 mg per kilo, intravenously. Injection of 0.4 to 0.5 cc filtered Higgins Eternal Black ink into renal artery was completed in 5 seconds, renal vessels were clamped 5 seconds after end of injection. The injection was through a fine hypodermic needle, sometimes with and sometimes against the stream. The kidneys were removed soon after; 3 to 6 blocks taken from different parts of the kidney were put into 10% formalin over night and frozen sections of 100 micra cut. From 7 to 12 sections of each block were counterstained with eosin and permanently mounted. With this technic the ink-free as well as the ink-containing glomeruli are easily seen and the proportion of injected to uninjected readily determined in a very large sample. Since each section contained 200 to 800 glomeruli, with 30 to 50 sections from each kidney, there were 10,000 to 30,000 glomeruli inspected with each kidney.

In every case it was found either (a) that every glomerulus was injected or (b) that the distribution of injected and uninjected was such as to indicate that failure of injection was due to the manner of distribution of ink in the larger preglomerular vessels rather than to closure of the glomeruli themselves or of the afferent arterioles.