Comparison of the activities of some dehydrogenases in the juxtaglomerular complex of kidneys of Wistar rats and desert rats (Meriones unguiculati)

Summary The authors compared the enzyme histochemical activities of some dehydrogenases in the macula densa, the Goormaghtigh cells and the epithelioid (or juxtaglomerular) cells in the kidneys of desert rodents (Mongolian Gerbils) with those of the Wistar rats.The macula cells (Table 1), which in the Wistar rats are clearly distinct from the non specific epithelial cells of the distal convolution, show, in the desert rats, noticeable fluctuations. Their enzyme histochemical reactions are often weaker than those of the distal convolution cells, with the exception of the NAD-tetrazolium-reductase activity.The Goormaghtigh cells (Table 2) in the kidneys of the Meriones have a much larger enzymatic spectrum than in the Wistar rats. Here also, we find functional variations in the examined desert species.In the epithelioid cells (Table 3) we observed a somewhat weaker enzymatic activity in the Meriones. These cells contain no secretion granules, this making their diagnosis difficult.     

Studies of the activity of various dehydrogenases in the desert rat (Meriones unguiculati) nephrons]

Researches about the Activity of some Dehydrogenases in the Nephrons of Desert Rats (Meriones unguiculati).--Our desert rats Meriones unguiculati (Mongolian Gerbils) show--also when held under the same experimental conditions as our other laboratory rodents (Wistar rats and white mice)--a somewhat different enzyme histchemical behaviour of these nephrons. The essential difference in the Meriones is that their distal convolutions display on the whole stronger enzyme activities compared as well with the proximal convolutions of the same kidneys, as with the distal convolutions of Wistar rats.     

The normal juxtaglomerular apparatus in the human kidney. A morphological study.

Out of 49 serially studied juxtaglomerular apparatuses, 6 typical variants from two normal human kidneys were reconstructed graphically. The agranular Goormaghtigh cells filled the entire space between the macula densa, the afferent and the efferent arterioles and the glomerular mesangium. The Goormaghtigh cells were always in direct contact with all the other structures. They also invariably continued into the glomerular mesangium. The distal tubule regularly showed widening in the macula densa segment and, at this level, there was considerable variation in the shape of the distal tubule. Direct contact between the macula densa and the hilar arterioles was not always present, the area of contact was usually greater with the afferent than with the efferent arteriole.     

Ultrastructural and morphometric aspects of the juxtaglomerular apparatus in the monkey kidney

Summary The authors describe the ultrastructure of the juxtaglomerular apparatus in five adult male Cebus apella monkeys and communicate morphometric data of the macula densa.In comparison with several species of rodents examined before, the macula cells of the monkey contain many more mitochondria and possess a particularly thick basal membrane. The relative volume of the nuclei is slightly smaller than in rodents.The Goormaghtigh cells of the monkey resemble those of the other animals investigated.The epithelioid (or juxtaglomerular) cells do not contain secretory granules. This observation reminds one of the behavior of the epithelioid cells of guinea pigs.Dedicated to Professor Dr. med. G. Petry (Marburg/Lahn) on the occasion of his 65th birthdayThe authors wish to thank Professor Dr. G. Peters, Head of the Institute of Pharmacology, and Professor Dr. F. Roch-Ramel for kindly having provided the monkey kidneys     

Studies on the histochemistry of phosphatase enzymes in the juxtaglomerular complex

Summary The localisation of alkaline-, adenosine tri-, glucose-6- and acid phosphatase was studied in the juxtaglomerular complexes of rat, mouse and human kidneys. An alkaline-and adenosine triphosphatase active region was observed between the macula densa, Goormaghtigh cell group and in the interstitium of the latter. The adenosine triphosphatase activity extended into the lateral cell membranes of the macular cells and in properly incubated sections it did not appear among other distal tubular cells. The granular juxtaglomerular cells were ATP-ase negative. The cells of the human macula densa and the granular juxtaglomerular cells of the rat and mouse showed acid phosphatase activity. The glucose-6-phosphatase reaction, accomplished at acid and alkaline pH, was negative in the JG complex of all three species. The possible role of these enzymes in the function of the JG complex also has been discussed.     

Pericapsular smooth muscle cells in renal corpuscles of the Mongolian gerbil

Summary During the course of a systematic investigation of the renal corpuscles in various desert rodents (Meriones unguiculati, Meriones shawii, Psammomys obesus, and Dipodymis), a thickened Bowman's capsule was observed light microscopically in some kidneys of adult Meriones unguiculati (Mongolian gerbil). Electron microscopic studies show that this unusual finding may depend on the presence of one or two layers of typical smooth muscle cells adjacent to the outer surface of the basal lamina. In the kidneys of other species of desert rats examined, no pericapsular smooth muscle cells were observed.     

Quantitation of glucose-6-phosphate dehydrogenase activity in cortical fractions of the nephron in sodium-depleted and sodium-loaded rabbits

Summary Glucose-6-phosphate dehydrogenase activity was measured quantitatively in isolated cortical fractions of the nephron in sodium-depeleted and sodium-loaded rabbits. The samples consisted of isolated fractions of macula densa, proximal convoluted tubule, distal convoluted tubule and glomerulus. In sodium-depleted rabbits enzyme activity was identical to that of normal rabbits. In sodium-loaded rabbits a significant decrease in enzyme activity was found in the macula densa and proximal convoluted tubule. However, using conventional histochemical incubation methods semiquantitative estimation of glucose-6-phosphate dehydrogenase showed a slight decrease in enzyme activity in the macula densa and distal convoluted tubule, and a slight increase in the proximal convoluted tubule during sodiumdepletion. During sodium-load a pronounced decrease in enzyme activity was seen in the macula densa and distal convoluted tubule. These results show that semiquantitative histochemical evaluation of changes in enzyme activity is less reliable than the more precise quantitative method especially when there are only slight changes in enzyme activity. Only where there were marked changes in histochemical enzyme activity might the results of quantitative and semiquantitative methods be in accord.     

Morphometric and enzyme histochemical behaviour of the kidney of young rats before and after unilateral nephrectomy.

Four week old male Wistar rats were unilaterally nephrectomized, and one, two, four, fourteen, and twenty-eight days after the operation the remaining kidneys were removed for morphological examination--including measurement of diameters of the tubules--and for histochemical investigation of enzymatic activities in the nephrons. The following enzymes were examined: succinate DH, lactate DH, alpha-glycerophosphate DH, isocitrate DH, glucose-6-phosphate DH, cytochrome oxidase, adenosine triphosphatase, alkaline and acid phosphatases. In comparison with kidneys of control animals of the same age and sex, the hypertrophy of the remaining kidney was found to be, even in these young rats, entirely due to enlargement of preexisting nephrons. The measurements have indicated that the hypertrophy was most distinct between the second and fourth day after uninephrectomy. Four weeks after the operation the diameters of proximal and distal tubules were about 21% and 18% respectively bigger in the uninephrectomized animals than in the corresponding controls. This increase in size was accompanied by some changes in intensity of enzymatic staining reactions; after an initial diminishment, a graduate increase in activity of almost all the observed tubular enzymes was found; this seems to be the expression of the functional compensation by the remaining kidney.     

The juxtaglomerular apparatus in the avian kidney

Summary The domestic fowl has two types of glomerulus (mammalian and reptilian type). 30 of each were studied morphometrically in semi thin and PAS-stained sections. The juxtaglomerular apparatus was larger in the mammalian type, but complete in both, containing macula densa, Goormaghtigh (lacis) cells and hilar arterioles. Granular epithelioid cells were occasionally found in the afferent arterioles and within the glomerulus in the mammalian type only.All glomeruli studied had a prominent mesangial cell mass (MCM), which was larger in mammalian type glomeruli. Hilar arterioles often penetrated the mesangial cell mass and regularly ramified within it. There was always extensive direct contact between the Goormaghtigh cell mass and the macula densa on the one side and the MCM on the other. In mammalian type glomeruli, the afferent arterioles were invariably found centrally within the MCM, but in the reptilian type no distinct pattern was found. The close relationship between the MCM and the hilar arterioles, especially in mammalian type glomeruli, suggests that the MCM regulates the glomerular filtration rate.     

The morphological basis of fluid balance in the interstitium of the juxtaglomerular apparatus

Summary The morphological basis of fluid balance in the interstitium of the juxtaglomerular apparatus (JGA) was reevaluated in rats, mice and Tupaia. Three ultrastructural features in the region of the vascular pole of the renal corpuscle are described that may be important for the fluid balance in this region: (1) podocyte foot processes in the parietal layer of Bowman's capsule, (2) endothelial fenestrations in the wall of the incoming afferent arteriole, both facing Goormaghtigh and epithelioid cells, and (3) the mesangial type lining of the glomerular stalk. With respect to the relevant pressure gradients, this morphology may provide the basis of bulk-fluid flow directed to the interstitium of the JGA including the Goormaghtigh cell field. Thus, the fluid balance in the lacis area and, consequently, the tubulo-glomerular feedback mechanism, probably does not solely depend upon the reabsorptive transport of the macula densa. Similar considerations may be valid for the humoral control of renin secretion from juxtaglomerular epithelioid cells.These studies were supported by the German Research Foundation within the SFB 90 Cardiovasculäres System     

Morphometric and enzyme histochemical behaviour of the kidney of young rats before and after unilateral nephrectomy

Summary Four week old male Wistar rats were unilaterally nephrectomized, and one, two, four, fourteen, and twenty-eight days after the operation the remaining kidneys were removed for morphological examination—including measurement of diameters of the tubules—and for histochemical investigation of enzymatic activities in the nephrons. The following enzymes were examined: succinate DH, lactate DH, α-glycerophosphate DH, isocitrate DH, glucose-6-phosphate DH, cytochrome oxidase, adenosine triphosphatase, alkaline and acid phosphatases. In comparison with kidneys of control animals of the same age and sex, the hypertrophy of the remaining kidney was found to be, even in these young rats, entirely due to enlargement of preexisting nephrons. The measurements have indicated that the hypertrophy was most distinct between the second and fourth day after uninephrectomy. Four weeks after the operation the diameters of proximal and distal tubules were about 21% and 18% respectively bigger in the uninephrectomized animals than in the corresponding controls. This increase in size was accompanied by some changes in intensity of enzymatic staining reactions; after an intial diminishment, a graduate increase in activity of almost all the observed tubular enzymes was found; this seems to be the expression of the functional compensation by the remaining kidney. Paper dedicated to Professor Dr. Drs. h. c. W. Bargmann (Kiel) in honour of the 70th anniversary of his birthday.     

Enzymes of the glucuronic acid pathway in Wistar and Gunn rats and their heterozygotes

A significant difference in UDP glucuronyltransferase activity (with p-nitrophenol as an acceptor) was found in the liver and kidneys of homozygous Wistar and Gunn rats. There was also a significant difference in hepatic UDP glucuronyltransferase activity between homozygous Wistar and heterozygous Gunn rats when the enzyme preparations were first activated by adding surfactants to the reaction mixture. This determination of surfactant-activated UDP glucuronyltransferase can be used to distinguish Wistar rats from heterozygous Gunn rats. Other enzymes of the glucuronic acid pathway were also studied in the liver and kidneys of homozygous Wistar and Gunn rats, but no differences were found.This study has been supported by grants from the U.S. Public Health Service (AM-06018-09 and the National Research Council for Natural Sciences, Finland.     

Na,K-ATPase in kidneys of rats with hereditary hypertension induced by stress]

It has been found that Na, K-ATP-ase activity in microsomal fraction obtained from the medullar layer of kidneys of stress-sensitive hypertensive rats (SSHR) which were subjected to stress effects is lower by 20-40% than that in the Wistar rats. In hypertensive animals the stress (30-min immobilization) has led to a considerable increase in blood tension. Values I50 for ouabain and dependence of activity on the ratio of Na and K ions in the medium are similar in animals of both lines subjected to the stress. There are also no considerable differences in the protein composition of microsomal fraction from kidneys of rats of both lines. The effects which increase permeability of vesicules (channel-forming agent alamecytin, lubrol WX, freezing-thawing) activate Na,K-ATP-ase in the preparation from the kidneys of rats of the both lines. Under maximum activation there is a removal of differences in activity of the enzyme obtained from the tissues of the SSHR and Wistar animals after the stress action. Blood serum of SSHR rats after the stress inhibits purified Na,K-ATP-ase to the greater extent than the Wistar rat blood serum after the same effect. It is supposed that differences in Na,K-ATP-ase activity in microsomal fraction from the kidneys of rats of the above lines are stipulated by the differences in the "latent" ATP-ase activity.     

Histochemistry of the juxtaglomerular apparatus in the toad Bufo bufo

Summary An investigation regarding the question of whether there exists a macula densa as part of the juxtaglomerular apparatus in the kidney of amphibians has been carried out. With the aid of a histochemical reaction for glucose-6-phosphate dehydrogenase activity, the presence of a macula densa zone as a specialized part of the distal tubule in the toad Bufo bufo was demonstrated. The functional significance of the high glucose-6-phosphate dehydrogenase activity in the macula densa cells is discussed.     

Quantitative measurement of glucose-6-phosphate dehydrogenase in cortical fractions of the rabbit nephron

A quantitative fluorimetric method is described for estimating the activity of glucose-6-phosphate dehydrogenase in isolated fractions of rabbit nephron from the superficial part of the renal cortex: macula densa, proximal convoluted tubule, distal convoluted tubule and glomerulus. The mean activity in the macula densa region was 2.5 X 10(-18) mol/micrometers 3/min, which was about twice the mean activity of the proximal and distal tubular cells and four times that of the glomeruli. As glucose-6-phosphate dehydrogenase is located in the cytoplasm, the average cytoplasmic enzyme activity of the different tubular cells was calculated: macula densa activity was 4.0 X 10(-18) mol/micrometers 3/min whilst proximal tubular cells showed about a third, and distal tubular cells about a quarter of this activity.     

Ultracytochemical localisation and comparison of adenyl cyclase activities in pineal bodies of Wistar rats and mongolian gerbils

Summary In the pineal bodies of Wistar rats and mongolian gerbils (Meriones unguiculati) the main concentration of adenyl cyclase was found in capillary endothelial cells, their basal laminae, pericapillary amorphous material and in nerve endings. In the intercellular clefts between the rat pineal cells there was no adenyl cyclase activity, but a considerable amount of this enzyme was detected in the gerbils. The adenyl cyclase lacks completely in the pinealocyte cytoplasms of both species. It was concluded that the gerbil pineal cells may be more reactive to various hormonal influence than those of the rat.With the technical assistance of Miss Ch. Thommen and Mr. P.-A. MilliquetDedicated to Professor Dr. med. O. Bucher on the occasion of his 65th birthday     

Semiquantitative histochemical investigation of lysosomal enzyme activities in the aortic endothelial cells of rats with renal hypertension

To obtain information about changes in lysosomal enzyme activities in the aortic endothelial cells in arterial hypertension, semi-quantitative histochemical investigations of acid phosphatase (Ac-Pase) and N-acetyl-beta-glucosaminidase (NAGase) activities in the aorta of rats with renal hypertension were performed on "H?utchen" monolayer preparations. The aortic endothelial cells in renal hypertensive animals showed increased Ac-Pase and NAGase activities compared with those in control normotensive rats and tended to increase with advancing age. These results, like our previous data from spontaneously hypertensive rats (SHR), indicated that degeneration of endothelial cells, expressed by increased lysosomal enzyme activity, was accelerated by hypertension, and the possible participation of genetic factors in the activation of these enzymes in SHR was ruled out. Increased lysosomal enzyme activity may be involved in the development of other hypertensive vascular changes.     

Effect of hypoosmotic stimulation of the gastrointestinal mucosa on the activity of NA+, K+-atpase of epithelial cells in the small intestine and kidney in rats]

The experiments on Wistar rats have shown that intragestral injection with mannitol hypotonic solution (20 mmol/l) causes the significant activation of Na+, K(+)-ATPase of duodenum and distal intestine epithelial cells, kidney cortex cells, but does not affect the brain cortex of Na+, K(+)-ATPase activity. Simultaneously the activator of enzyme (AE) enters blood serum of rats, its activity is revealed by blood serum addition to homogenates of tissues of control rats. It is assumed that AE is produced in duodenal and intestinal mucosa released to blood after stimulation of mucosal surface by hypotonic solutions and included into the osmoregulation processes on the Na+, K(+)-ATPase level.     

Transglutaminase activity along the rat small bowel and cellular location

A recent report indicates a relationship between human transglutaminase (TG) jejunal mucosa activity and celiac disease. We investigated the enzyme distribution along six consecutive small bowel segments of mucosa and tested TG activity on brush border membranes obtained from whole mucosa homogenate in Wistar rats. TG activity was significantly present in jejunal mucosa even if mostly detected in the distal part of small intestine. Our study indicates highest enzymatic activity in the subcellular fraction containing organelles and cellular membranes (66.8%) while a 7% activity was associated with the brush border fraction.     

Na+--K+-adenosine triphosphatase and some oxidoreductases in the kidney of rats with spontaneous hypertension]

The activities of the Na+--K+-ATPase, succinic dehydrogenase (SDH/, lactic dehydrogenase (LDH/ and glucose-6-phosphat dehydrogenase (G-6-PDH/ were studied in the cortex outer and inner medulla of the kidneys of rats with spontaneous hypertension (SHR) and were compared with those of control normotensive Wistar rats. The SHR aged 6--8 weeks had durint the prehypertensive and the early hypertensive stage the same enzymatic activities as control rats. Rats with a steady SH aged 16-22 weeks had low specific activity of the, Na+--K+-ATPase, SDH and LDH in the outer medulla. The latter can be associated with decreased intensity of the energy metabolism and a reduction of the active sodium transport in the ascending limb of the loop of Henle in the SHR rats and cold cause the phenomenon of exaggerated natriuresis characteristic of hypertension.