Enzymatic activity of the isolated glomerulus in normal and nephrotic rats.

Recent studies of the nephrotic kidney have implicated the glomerulus as the primary anatomic site of injury. Using the electron microscope, Farquhar, Vernier and Good (1) and other investigators have demonstrated that the most consistent and striking alteration is a lesion in the foot process of the glomerular epithelial cell. Hjelt, Stjernvall and Hallman (2), in a study of congenital nephrosis, found imperfectly formed or absent foot processes. Vernier, Papenmaster and Good (3), and Harkin and Recant (4) have described similar lesions of the foot process in experimental nephrosis induced by the aminonucleoside of Puromycin, and Piel (5) has made similar observations in nephrosis produced by antikidney serum. In the experimentally induced lesion, glomerular injury is found prior to tubular changes (4). With the recognition that relatively specific anatomic changes occur in the glomerulus in nephrosis, it seemed pertinent to determine if alterations occur in glomerular enzyme activities. The application of quantitative histochemical techniques seemed to be the most promising approach for such a study. Previous histochemical studies of kidney utilizing staining techniques have been "qualitative" in nature in that they demonstrated the presence or absence of enzyme, but could not quantify these enzymes. In addition, such studies have given most attention to the renal tubule rather than to the glomerulus. Quantitative histochemistry utilizing microchem-