The technique of superfusion

Abstract

1. The word superfusion is used to describe experiments in which suitable liquids run over tissues suspended in air. A new method of applying drugs to such tissues is described. 2. The value of supervised guinea-pig's ileum for the assay of histamine is confirmed. 3. Supervised rat's uterus may be used in assays involving oxytocin, the effective dose of which is about 0.02 milliunits. 4. Superfusion is particularly suitable for the study of slow-acting substances. This is illustrated by the analysis of the properties of "substance R," which comes from rat's intestine and causes a slow contraction of rat's uterus. This substance does not dialyse through cellophane, and is insoluble in 80% cold acetone and rather unstable in watery solution. Its properties resemble those of some proteolytic enzymes, but its identity has still to be established.