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

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.     

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     

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.     

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 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     

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.     

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.     

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.     

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.     

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.     

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.     

Molecular systematics of gerbils and deomyines (Rodentia: Gerbillinae,Deomyinae) and a test of desert adaptation in the tympanic bulla

Recent molecular studies in gerbils found multiple instances of discordance between molecular and morphological phylogenies. In this study, we analyse the largest molecular data set to date of gerbils and their sister group the deomyines to estimate their phylogenetic relationships. Maximum‐likelihood and Bayesian analyses were largely concordant, and both generally had high levels of node support. For gerbils, the results were generally concordant with previous molecular phylogenies based on allozymes, chromosomes, DNA/DNA hybridization and DNA sequences, and discordant with morphological phylogenies. None of the traditional gerbil tribes and subtribes were monophyletic. In addition, paraphyly was found in the genera Gerbillus, Gerbilliscus and Meriones as well as in five subgenera within Dipodillus, Gerbillurus and Meriones. Short branches separating taxa in small clusters within Dipodillus and Meriones suggest synonymy. Within deomyines, all genera and subgenera were monophyletic; however, two species groups within Acomys appear to contain synonymous taxa. We also find support for the discordance between molecular and morphological phylogenies in gerbils being partly due to convergent adaptations to arid environments, primarily in the suite of traits associated with inflation of the tympanic bullae. Relative bullar size does appear to be a desert adaptation and is correlated with aridity independent of phylogeny. Further, it varies more strongly along bioclimatic clines than between binary habitat classifications (desert versus mesic).     

In vivo bioassay to detect irinotecan-stabilized DNA/topoisomerase I complexes in rats

Irinotecan is an anticancer agent that stabilizes topoisomerase I/DNA complexes. So far, no test system has been reported for directly determining irinotecan-induced stabilization of topoisomerase I/DNA complexes in organs in vivo. We adapted an ‘in vivo complexes of enzyme to DNA’ (ICE) bioassay to assess irinotecan activity in the stomach, duodenum, colon and liver of male Wistar rats after a single treatment with irinotecan (100 mg/kg body weight, intraperitoneally). This was compared to the control group receiving 0.9% sodium chloride intraperitoneally. In addition, the DNA strand breaking properties of irinotecan were measured in mucosal cells from the distal colon by single-cell gel electrophoresis (comet assay) to investigate the association of topoisomerase poisoning and DNA damage in vivo. A single dose of irinotecan significantly increased amounts of topoisomerase I covalently bound to DNA in stomach, duodenum, colon and liver. Concomitantly, the irinotecan-treated group showed significantly higher amounts of DNA strand breaks in colon mucosa cells compared to the control group. The ICE bioassay and the comet assay represent two test systems for investigating the impact of topoisomerase I poisons on DNA integrity in colon tissues of Wistar rats.     

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.     

Concentrations of copper, iron, and zinc in the major organs of the wistar albino and wild black rats

The concentrations of copper, iron, and zinc in the major organs of Wistar albino (Rattus norvegicus) and wild black rats (Rattus rattus) were measured by means of atomic absorption spectroscopy. The copper levels in the kidneys and liver of the Wistar albino rats (WARs) were significantly higher (p<0.05) than in the wild black rats (WBRs). There were no significant differences in the concentrations of zinc in the liver, lungs, kidneys, and brain between the two study groups, but zinc was significantly higher in the spleen (p<0.05) and lower in the heart (p<0.05) of WAR, compared to WBRs. Iron was significantly higher (p<0.05) in the heart and spleen of WBRs, compared to WARs. There were no extreme differences in the organ concentrations of trace elements between the two species, but, cumulatively, the WARs tend to have higher metallic concentrations in their system than the WBRs. The potential of these differences on the experimental results should not be overlooked and will serve as basis to further consider the complex interrelationships of these animals in their microenvironments and macroenvironments.     

Ultrastructural organization of the transition from the distal nephron to the collecting duct in the desert rodent Psammomys obesus

Summary The transition from the nephron to the collecting duct is formed by three tubular segments (convoluted part of the distal tubule, connecting tubule, cortical collecting duct), which in the desert rodent, Psammomys obesus, transform gradually from one segment to the next, due to intermingling of their different cell types.The convoluted part of the distal tubule (DTC) starts abruptly, shortly beyond the macula densa and initially is homogeneously composed of characteristic DTC-cells. Subsequently, the DTC-cells intermingle with intercalated cells. The first appearance of the connecting-tubule cell, which gradually replaces the DTC-cell, is regarded as the beginning of the connecting tubule. The major portion of the connecting tubule is lined by connecting-tubule cells and intercalated cells. The first appearance of the principal cell between them defines the beginning of the cortical collecting duct, which in the medullary ray is lined by principal and intercalated cells only.Each cell type is described in detail and discussed in relation to the assumed function of the tubular segments.Interspecies differences in the cellular composition of the transitional zone from the nephron to the collecting duct are discussed in relation to the different organization of the collecting duct system.     

The intramucosal distribution of gastric alcohol dehydrogenase and aldehyde dehydrogenase activity in rats

Using qualitative and microquantitative histochemical techniques, alcohol dehydrogenase and aldehyde dehydrogenase activity was studied in the gastric mucosa of male and female rats. Alcohol dehydrogenase was demonstrated by staining reactions with maximum activity in surface and neck cells and with clearly weaker activity also in parietal cells. Aldehyde dehydrogenase could be detected in surface and neck cells, and also to a comparable degree in the parietal cells. Quantitative analyses of microdissected samples yielded high values for alcohol dehydrogenase activity exclusively in the superficial part of the gastric mucosa, whereas low-K _m aldehyde dehydrogenase activity showed a decreasing gradient from the surface to the deeper parts of the mucosa. Sex differences could not be confirmed.Dedicated to Professor Dr. K.S. Ludwig on the occasion of his 70th birthday     

The problem of diabetic angiolopathy in sand rats (Psammomys obesus)

No diabetic angiolopathy was found in the retinas, kidneys and skeletal muscles of protodiabetic and overtly diabetic sand rats. The terminal blood vessels were investigated using histological, enzyme histochemical, immunofluorescence microscopic, autoradiographic and electron microscopic methods. There seems to be little or no connection in sand rats between the diabetic metabolism syndrome and the metabolic process leading to angiolopathy.     

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.