Enzyme Activity Staining

A histochemical procedure for localizing and evaluating leukocyte alkaline phosphatase activity in smears of blood and marrow.

With the technical advances of the past few decades, there has been increasing emphasis in neurophysiology and neuropharmacology on studies at the cellular and subcellular levels, as illustrated by most of the chapters in the present volume. The magnitudes and sequences of the electrical signs associated with neuronal activity could be defined accurately only after the development of reliable single unit and intracellular recording techniques. At the same time, the electron microscope has yielded knowledge of the morphological details of nervous tissue well beyond its known physiological correlates. However, the chemistry of the structures and specific reactions involved in nervous function can for the most part be described only at the tissue or relatively gross cellular level, and the cytological details as to where the various reactions occur are largely conjectural.

Cytological Distributions and Physiological Functions of Cholinesterases

Summary

Researches of the past ten years bearing on the physiological significance of the common acid and alkaline phosphomonoesterases may be summarized in the following facts and concepts, (i) The alkaline phos-phomonoesterase appears to be a salt-soluble, the acid a water-soluble, substance; both consist of a metallic coenzyme and a protein-like carrier. Neither depends oh sulphydryl groups for activity, but the alkaline phosphatase seems to require amine and phenolic hydroxy! groups; it is affected only by strong oxidizing agents. There is not yet any incontestable evidence that alkaline phosphomonoesterases of different sources are not identical. (2) Phosphatases probably catalyse only hydrolyses, not syntheses. (3) The content of both phosphatases in the blood serum is characteristic of age and physiological state, and is used in the diagnosis of bone and liver disorders; biliary obstruction results in elevation of serum alkaline phosphatase probably because phosphatase is normally excreted by way of liver and gut, but other explanations are possible. Diet influences serum alkaline phosphatase level. (4) The study of phosphatase function has been advanced by the development of techniques for the histochemical demonstration of acid and alkaline phosphatases. (5) It is certain that alkaline phosphatase is indispensable in normal ossification; it is generally instrumental in abnormal calcifications, but in a few cases calcification occurs without it. (6) Glycolysis seems to accompany normal bone formation, but this fact does not clarify all the unsolved problems of ossification. (7) Hormones and vitamins influence both alkaline phosphatase activity and bone formation. (8) In kidney tubules alkaline phosphatase probably functions in dephosphorylating sugar molecules that are removed from the tubular fluid by phosphorylation. The enzyme is present at other sites where it might serve in a similar manner. (9) Phosphatases are commonly found in the cytoplasm of growing, regenerating, and secreting cells in which protein synthesis is being carried on; there appears to be a correlation in such cells between content of pentosenucleic acid and of phosphatase. In dividing nuclei, phosphatase parallels desoxyribonucleic acid. (10) Acid phosphatase is found in seminal fluid, and may help to nourish the sperm. (11) The occurrence of two common phosphomonoesterases with widely different pH optima may indicate a mechanism for allowing two dephosphorylating steps to go on simultaneously in a single cell. In tissues which carry on much traffic in glycogen, acid phosphatase is possibly provided to prevent bone formation. (12) The actual role which the phosphatases play in the physiology of the organism will be understood only with elucidation of the complete enzyme systems of which the phosphatases are a part.

The physiological significance of the phosphomonoesterases

1. Die vorliegende Arbeit berichtet uber systematische histoenzymatische Untersuchungen und befast sich mit grundsatzlichen und methodischen Problemen sowie mit Untersuchungen zur vergleichenden Histoenzymatik beim Menschen und verschiedenen warmblutigen Wirbeltieren.

Histochemischer Nachweis hydrolytischer Enzyme mit Hilfe der Azofarbstoffmethode

A coupling histochemical azo dye test for alkaline phosphatase in the kidney

SummaryThe location of the alkaline phosphatase in the kidney of the rat, mouse, and human shown by the use of a histochemical azo dye test is mainly in the proximal convoluted tubule. This distribution agrees substantially with that obtained by the silver technic of other investigators. Minor differences in the enzyme distribution in the three species are described.

Josephine Junge

Papers

A coupling histochemical azo dye test for alkaline phosphatase in the kidney

Distribution of Alkaline Phosphatase in Kidney Following the Use of Histochemical Azo Dye Test