Histochemical studies of alkaline phosphatases in the tissues of the rat using frozen sections. II. Substrate specificity of enzymes hydrolyzing adenosine-triphosphate, muscle- and yeast-adenylic acids, and creatine-phosphate at high pH; the histochemical demonstration of myosin ATP-ase

Localized areas of high alkaline phosphatase activity in the terminal arterial tree

Fresh frozen skeletal muscles of rats, rabbits, and humans were sectioned in a cryostat. Sections 12 to 32 micra thick were incubated in a substrate solution for the histochemical demonstration of non-specific alkaline phosphatase activity. A modified azo dye coupling technique was used at pH 9.5. Localized areas of high enzymatic activity were found in specific and well defined areas along the terminal arterial tree, in addition to the activity which has been previously described in capillary endothelium. Arterial branches with luminal diameters of 25 micra or less showed staining of their endothelium starting abruptly at their origin from the parent vessel and fading distally. Smaller arterial branches showed the same localization of enzymatic activity and stained more intensely. Other organs of rats surveyed showed arterial branches with the same pattern of staining. Identical results were obtained using the Gomori technique for alkaline phosphatase. Extensive saline perfusion of the vascular tree did not affect the observed localization of enzymatic activity. The enzymatic activity described may be part of the mechanism regulating the blood flow.

A new histochemical method for magnesium actomyosin adenosine triphosphatase at physiological pH

A new lead-precipitation technique for demonstrating magnesium-activated actomyosin adenosine triphosphatase (ATPase) at physiological pH and electrolyte levels in fixed skeletal muscle sections is reported. This method is compared with standard acid- and alkali-denatured muscle stained for calcium myosin ATPase as well as calcium-formalin denatured and pyrophosphate-formalin denatured muscle also stained for calcium myosin ATPase. The technique was developed using hamster skeletal muscle; however, it has also been applied to human, rat, and cat muscle. The fiber-type staining intensities of the formalin-denatured magnesium actomyosin ATPase closely resemble those of the formalin-denatured calcium myosin ATPase in rodents, but intensities in Type 1 fibers are reversed relative to calcium myosin ATPase in human muscle. Cat muscle shows intermediate characteristics.

Influence of L-thyroxine upon enzymatic activity in the renal tubular epithelium of the rat under normal conditions and in mercury-induced lesions. I. Histochemical studies of alkaline phosphatase, acid phosphatase, adenosine- tri-phosphatase and leucine-aminopeptidase

HgC12-induced renal tubular lesions in the rat present histochemically with a transitory decrease of alkaline phosphatase, adenosinetriphosphatase (ATPase), and leucine-aminopeptidase activity. The toxic alterations of enzyme activity were more pronounced in the pars recta of the proximal tubule and in the loop of Henle, as compared with the tubulus contortus I. L-thyroxine treatment leads to an accelerated reversal of that enzymatic defect, followinga characteristic pattern, and to a differentiating increase of acid phosphatase and ATPase activity in certain parts of the normal renal tubule. The observations are discussed with reference to the specific mode of action of sublimate and l-thyroxine upon the tubular enzymes and to the well-known metabolic and functional influences of thyroid hormone on the kidney.