Claude Petitclerc

Heterogeneous distribution of alkaline phosphatase and γ-glutamyl transpeptidase in the mouse nephron

In the mouse nephron, ALP and gamma-GT were found to be heterogeneously distributed along the proximal tubule. For both enzymes, 4 large categories of tubules could be recognized on the basis of the enzymatic activity: intense; intermediate; weak; negative. The localization of ALP and gamma-GT was in opposite gradient along the proximal tubule and it apparently corresponded to the 3 sequential segments S1, S2, and S3. In fact, S1 could be identified with certainty because this first portion was often seen attached to the renal corpuscle. This segment displayed a very intense ALP activity (category 1), but a weak one for gamma-GT (category 3). Intermediate tubules for ALP and gamma-GT activities (category 2) seemingly were parts of S2. Those tubules where ALP activity was weak (category 3) while that of gamma-GT was intense (category 1) probably belonged to S3. As a result, it becomes possible to clearly distinguish the segments S1, S2, and S3, not only on a structural and biochemical basis but as well by the localization of brush border enzymes. Distal tubules showed no enzyme activity (category 4). In other respects, the presence of ALP and gamma-GT on the parietal layer of Bowmans capsule strongly suggests that these tall cylindrical cells are morphologically and enzymatically identical to those of the S1 segment, and that they might have similar functional roles.

Presence of alkaline phosphatase and γ-glutamyl transpeptidase on the parietal layer of Bowman's capsule

Generally, the parietal layer of Bowmans capsule in the mammal kidney consists of a squamous epithelium resting upon a basement lamina. However, tall cylindrical cells resembling those of the proximal tubules were observed on the outer wall of Bowmans capsule in the mouse and rat kidneys. These cells were provided with an apical brush border and were positive for alkaline phosphatase and gamma-glutamyl transpeptidase suggesting phosphate and amino acid transport at the capsular level.

Electron-microscopic demonstration of alkaline-phosphatase activity in the juxtaglomerular apparatus.

SummaryIn the rat nephron, alkaline phosphatase (ALP) was observed, with the light microscope, to be present on the brush border of the proximal tubule and in a small band of cells of the juxtaglomerular apparatus. With the electron microscope, ALP activity could not be demonstrated in the macula densa cells proper, but was seen for the first time in a narrow zone of cells interposed between the macula densa and the vascular pole of the renal corpuscule. The lead phosphate precipitates were precisely localized on the plasma membranes which form an intricate network of cytoplasmic interdigitations. Since ALP is known to be involved in some steps of phosphate transport, the present morphological data might be considered as an indication for a role of phosphate as a signal ion for the autoregulation of glomerular filtration.

Alcohol-related changes in uricemia.

Abstract The proportion of users of alcoholic beverages in a probability sample of a natural population has been found to be low in hypouricemic groups and high in hyperuricemic ones at any one age and in either sex. Normouricemic populations are characterized by rates of users of alcoholic beverages which are intermediate between hypouricemic and hyperuricemic groups. These same groups do not manifest similar patterns in prevalence rates of users of cigarettes, oral contraceptives, tranquillizers or salicylates.

Simultaneous visualization of alkaline phosphatase and γ-glutamyl transpeptidase in kidney sections

An histochemical method is presented to simultaneously localize, for the first time, alkaline phosphatase (ALP) and gamma-glutamyltranspeptidase (gamma-GT) in the kidney. The reaction product of ALP activity appears as a dark brown precipitate of lead sulfide, while a bright red copper chelate of an azo dye (Fast blue BBN salt) final product indicates sites of gamma-GT activity. The amalgamation of Mayaharas (ALP) and Rutenbergs (gamma-GT) techniques resulted in the demonstration of various categories of kidney tubules, according to the staining reaction of the cell brush borders: Black tubules where ALP predominates; Intermediate tubules showing a mixture of brown and red precipitates; Red tubules indicating a prevalence of gamma-GT activity; Negative tubules. A possible relation might exist between the staining characteristics observed and the different proximal tubule segments, thus allowing their distinction. In addition, this technique has the advantage to permit the concomitant study of ALP and gamma-GT distribution on the same tissue section instead of serial sections, so reducing the number of manipulations and observations as well as the amount of tissue required.

Identification of proximal tubule segments in the mouse nephron by simultaneous visualization of alkaline phosphatase and γ-glutamyl transpeptidase

ALP and gamma-GT are 2 brush border enzymes that can be individually demonstrated on adjacent sections by the histochemical methods of Mayahara (ALP) and Rutenberg (gamma-GT). On the basis of each enzyme activity, it was possible to recognize different categories of tubules in the mouse nephron. In fact, both enzymes were heterogeneously distributed along the proximal tubule, but in opposite gradients. The various staining intensities probably corresponded to proximal segmentation, but were sometimes difficult to evaluate. A technique was perfected to localize both enzymes in the same tissue section. Since each enzyme produced a distinct type of colored precipitates (ALP: black, gamma-GT: red), 4 categories of tubules could be identified, according to staining characteristics: 1. black tubules where ALP activity was predominant, corresponded to S1 segments, 2. black and red tubules where the 2 activities were about equivalent, were considered as parts of S2, 3. red ones where gamma-GT activity was high, were identified as portions of S3, 4. negative tubules where no activity was apparent, represented distal and straight collecting tubules. In addition to economize time and tissue, this simple technique permits to easily estimate variations in enzyme activities that probably correspond to structural and functional differences in the segments of the proximal tubule.