The histochemical distribution of aniline hydroxylase in rat tissues.

Abstract

The histochemical technique of Gangolli & Wright (1971) was used to detect aniline hydroxylase activity in a number of rat tissues. A high degree of activity was found in the adrenals (fasciculata and reticularis zones), the cortical tubules of the kidney, the epithelium of the small intestine, cardiac and ‘red’ striated muscle and the corpus luteum. Less activity was found in the placenta, the endometrium in pregnancy and the epithelium of the bronchi and large intestine. Weak activity was present in the anterior pituitary gland, smooth muscle of the intestine, uterus and bladder, skin and bladder epithelium and ‘white’ striated muscle. These was no activity in the thyroid and parathyroid, lymphoid tissue and endometrium. In all tissues the enzyme activity was denoted by a brownish deposit in the form of discrete small granules. The staining reaction was totally abolished when tissues were incubated in an atmosphere of a mixture of carbon monoxide and oxygen (80∶20 v/v), or in nitrogen, or by the omission of aniline from the incubation medium. Although it is not certain whether aniline hydroxylase activity in extrahepatic tissues has the same connotation and significance as microsomal hepatic aniline hydroxylase, its successful inhibition by carbon monoxide and nitrogen in a wide variety of tissues indicates that the histochemical demonstration of this enzyme may merit consideration in the study of chemically induced cellular damage in a variety of organs.