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R Taugner

Publications and source records attributed to R Taugner.

At least 55 records · Page 3Linked to original sources
PubMed1984

Interendothelial junctions in kidney vessels.

The interendothelial junctions of all segments of the renal vasculature have been studied in eight species using the freeze-fracture technique. Three types of junctions have been found. Combinations of tight and gap junction elements are characteristic for interlobular arteries and proximal afferent arterioles. Continuous tight junction strands not subdivided into individual particles are typical for the glomerular arterioles close to the glomerulus and the vasa recta. The interendothelial junctions of glomerular and peritubular capillaries and cortical veins are characterized by slight elevations decorated with sparse arrays of particles on the P-face of the endothelial cell plasma membrane.

Animals↗
PubMed1984

Myoendothelial contacts in glomerular arterioles and in renal interlobular arteries of rat, mouse and Tupaia belangeri.

Cell contacts between elements of the tunica media and the intima in the afferent and efferent glomerular arteriole and in the interlobular artery were studied and evaluated semiquantitatively in thin sections of rat and mouse kidney. In the afferent arterioles, including their juxtaglomerular portion, contacts were seen between endothelial and smooth muscle cells, and between endothelial and granulated (renin producing) cells. The form of these musculo-endothelial contacts varied from simple appositions of perikarya and cell processes to extensive club-shaped indentations of endothelial cells into media cells (common) or media cells into endothelial cells (rare). Most of these cell contacts seem to contain myoendothelial gap junctions. Fewer, mostly club-shaped myoendothelial contacts were found in the interlobular arteries of rats and mice than in their afferent arterioles. Simple membrane appositions predominated among the numerous myoendothelial contacts of efferent arterioles. Similar results (without quantitative analysis) were obtained in the kidney of Tupaia belangeri. The myoendothelial contacts may allow the detection and propagation of mechanical (autoregulatory) and humoral stimuli.

Animals↗
PubMed1984

Interstitial and parenchymal cells in the pineal gland of the golden hamster. A combined thin-section, freeze-fracture and immunofluorescence study.

A combined thin-section/freeze-fracture study was performed on the superficial pineal gland of the golden hamster, comparing the parenchymal and interstitial cells of this animal with those previously investigated in rats. In contrast to rats, no gap junctions and gap/tight junction combinations could be found between pineal parenchymal cells of the hamster. Furthermore, the interstitial cells of the hamster pineal gland were found to have large flat cytoplasmic processes, which abut over large areas equipped with tight junctions. In thin sections, profiles of interstitial cell processes were seen to surround groups of pinealocytes. Interstitial cells and their sheet-like, tight junction-sealed processes thus appear to delimit lobule-like compartments of the hamster pineal gland. Because the classification of the interstitial cells uncertain, the expression of several markers characteristic of mature and immature astrocytes and astrocyte subpopulations has been investigated by indirect immunohistology. Many of the non-neuronal elements in the pineal gland are vimentin-positive glial cells, subpopulations of which express glial fibrillary acidic protein (GFA) and C1 antigen. The astroglial character of these cells is supported by the lack of expression of markers for neuronal, meningeal and endothelial cells. M1 antigen-positive cells have not been detected.

Animals↗
PubMed1984

Ultrastructural changes associated with renin secretion from the juxtaglomerular apparatus of mice.

Thin sections and freeze-fracture replicas were used to investigate the ultrastructural changes associated with renin secretion from the juxtaglomerular part of the afferent arteriole of male mice. Adrenalectomized animals in which renin secretion was stimulated by furosemide application and bleeding were also studied. Exocytosis of mature electron-dense granules was found in all experimental groups. Before extrusion, the region of granule facing the cell membrane changed, with vesicular and/or stacked membrane-like profiles and a small local protrusion of the granule membrane appearance of. Concomitantly, punctuate sites of fusion between the cell and granule membranes were observed. Later, unaltered amorphous, and altered membrane-like granule content was released from omega-shaped cavities into the extracellular space. In stimulated animals the alteration and extrusion of several closely apposed granules was reminiscent of compound exocytosis. Coated pits were frequently seen, suggesting specific retrieval of the former granule membrane. The collapsing silhouette of a depleted granule very rarely took the form of a saccule whose narrow membrane-bounded neck was continuous with the extracellular space. Observed were two additional events by which active and inactive renin may be released. Small electron-lucent vacuoles of undetermined origin fused with the cell membrane and, in stimulated kidneys, some epithelioid cell processes disintegrated. However, the interpretation of the related ultrastructural phenomena was uncertain.

Adrenalectomy↗
PubMed1984

Coexistence of renin and angiotensin II in epitheloid cell secretory granules of rat kidney.

The distribution of renin and angiotensin II (ANG II) in juxtaglomerular epitheloid cells of control and adrenalectomized rats was studied, using specific antisera and the protein A-gold technique in Lowicryl- and glycol methacrylate-embedded tissue. The matrix of virtually all mature secretory granules of epitheloid cells contains not only renin, but also ANG II. On adrenalectomy, the concentration of both renin and On adrenalectomy, the concentration of both renin and ANG II in the granule internum increases markedly, as indicated by the density of the immunolabel. Given the coexistence of renin and ANG II in the granule matrix, it is quite probable that, with each secretory event, a certain amount of ANG II is released together with renin. Further experiments will have to show if this amount of ANG II cosecreted with renin is sufficient to elicit immediate local intrarenal actions. ANG I, as well as angiotensinogen and converting enzyme, were not found in epitheloid cells. It is therefore inferred that ANG II is not generated intracellularly, but within the extracellular space and subsequently taken up by pinocytosis and incorporated into the secretory granules of epitheloid cells.

Adrenalectomy↗
PubMed1984

Renin immunohistochemistry in the mesonephros and metanephros of the pig embryo.

The occurrence and distribution of renin was investigated in meso- and metanephric kidneys of pig embryos in various gestational stages. The immunohistochemical peroxidase-antiperoxidase-method (PAP) was used on paraffin sections after application of an antiserum against mouse renin which cross reacts with pig renin. Renin immunoreactivity was already found in the mesonephros of 21 day pig embryos (crown-rump(CR)-length 12 mm) with the strongest reaction in the media of the juxtaglomerular afferent arteriole. Efferent vessels, mesonephric arteries, and the aortic wall also contained scattered renin-positive cells. In the definitive kidney, renin was not detected prior to the 25 mm CR-length-stage. In 45 mm embryos, immunocytochemical staining was observed not only in the media of kidney arteries and arterioles, but also in proximal tubules after pinocytic absorption of filtered renin. TEM-studies revealed that the media of both the mesonephric and the developing metanephric arteries and arterioles contains epithelioid cells whose ultrastructure is very similar to that of renin-producing cells in the adult organ. The observed distribution of renin-producing cells along the entire renal arterial tree points to the possibility that the major function of the renin-angiotensin system in the fetal animal is to participate in the stabilization of renal perfusion pressure.

Animals↗
PubMed1984

The afferent glomerular arteriole: immunocytochemical and electrophysiological investigations.

Immunocytochemical techniques were used for the localization of the different components of the renin-angiotensin system (RAS) within the kidneys of various species. Special attention was paid to the renin-secreting granulated cells located mainly in the media of the afferent glomerular arteriole. It was demonstrated that variations of kidney renin caused by stimulation or inhibition of the RAS are reflected in changes of the length of the renin-positive part of the afferent arteriole upstream from its entry into the glomerulus. During stimulation, plain smooth-muscle cells are transformed into renin-generating granulated cells. Likewise, the marked species differences in kidney renin are paralleled by corresponding differences in the renin-positive part of the afferent vessel. In this context, the site of action and the relative importance of the stimuli inducing renin secretion, i.e., the beta 1-adrenoreceptor, the mechanoreceptor, and the so-called macula densa mechanism are discussed. Whereas the microtopography of the RAS in the kidney has been at least partly understood, little is known about the stimulus-secretion coupling at the level of the individual granulated cell. Thus, adequate electrophysiological data about granulated cells might help to understand some still obscure phenomena, e.g., the inhibitory effect of Ca2+ on renin secretion. Our investigations in the hydronephrotic kidney preparation of the mouse show that granulated cells do not differ significantly from "plain" smooth-muscle cells in their electrical characteristics. They have a membrane potential of -55 mV and are spontaneously active. Both cell types are depolarized by noradrenaline and angiotensin II (AII), although they remain unaffected by isoproterenol. Since isoproterenol is known to stimulate renin secretion, our results indicate that stimulus-secretion coupling via the beta 1-adrenoreceptor is likely to proceed without changes of membrane potential in granulated cells.

Angiotensin I↗
PubMed1983

Angiotensin-like activity in resistance vessels. Immunocytochemical study in Chinese hamsters.

Angiotensin II (ANG II) was localized immunocytochemically in kidney and various other organs of the chinese hamster. In the kidney ANG II-like activity was found in the epitheloid cells of the juxtaglomerular apparatus as well as in the media i.e. the smooth muscle cells of arcuate and interlobular arteries and afferent arterioles. ANG II-like activity was also observed in the medial muscle cells of resistance vessels in other organs and tissues such as submandibular gland and brown adipose tissue. The site of synthesis of ANG II needs to be investigated but the data point to the possibility of an intracellular function of ANG II in smooth muscle cells of blood vessels.

Angiotensin II↗
PubMed1983

The specificity of angiotensin-antisera. A cautionary note.

Apparently monospecific antisera against the decapeptide angiotensin I (ANG-I) have been analyzed for their crossreactivity to the octapeptide angiotensin II (ANG-II). Whereas in the conventional displacement reaction of labeled ANG-I by ANG-II crossreactivities were in the order of 0.01%, the direct binding assay revealed crossreactivities of up to 20%. Both labeled ANG-I and ANG-II can be displaced completely from the antibody by an excess of either ANG-I or ANG-II. A similar relationship was seen with respect to the crossreactivity of ANG-II-antisera to ANG-I. - The data demonstrate that false positive immunocytochemical reactions may be obtained if the specificity of the reaction relies on the displacement reaction and the preabsorption of the antisera with the respective peptide. - These results may be pertinent for peptides other than the angiotensins.

Angiotensin I↗
PubMed1983

Cellular mechanisms of renin release.

In the isolated perfused rat kidney renin release is increased by physiological agents which stimulate adenylate cyclase activity, such as beta-adrenoceptor agonists, prostaglandins, histamine (histamine H2-receptor mediated) and adenosine (adenosine RA-receptor mediated). The role of adenylate cyclase and cAMP in the stimulatory pathway for renin release was confirmed by the effect of forskolin, a receptor-independent stimulator of adenylate cyclase, which also stimulated renin release. The intracellular calmodulin-calcium complex was identified as part of an opposing inhibitory pathway. This conclusion is based on the observation that various inhibitors of calmodulin stimulated renin release and that the calcium-dependent inhibition of renin release by angiotensin II was abolished in the presence of these inhibitors. The intracellular control mechanisms for renin release are discussed with respect to the vascular smooth muscle origin of renin-producing cells.

Adenosine↗
PubMed1983

Immunohistochemistry of the renin-angiotensin-system in the kidney.

Changes of the intrarenal localization and concentration of renin in comparison to those of angiotensin II (ANG II) are shown under various conditions of stimulation and inhibition of the renin-angiotensin-system. Evidence is presented that ANG II which is detectable by immunocytochemical methods in epitheloid cells is formed locally within the kidney either intra- or extracellularly. ANG II-like activity was found not only in the epitheloid cells of the JGA, but also further upstream in non specialized, "plain" smooth muscle cells of the renal arterial tree and in the medial muscle cells of resistance vessels in other organs and tissues. This ANG II-like activity of resistance vessels is increased in spontaneously hypertensive rats suggesting a possible role in the long-term regulation of blood pressure.

Adrenalectomy↗
PubMed1983

[Renal hypertension - a threatening complication of blunt kidney injuries].

The therapeutic management of renal trauma is mainly determined by the type and grade of kidney damage. However, imminent complications of renal trauma should already be considered during the primary therapy. The posttraumatic development of the arterial blood pressure was analysed in 153 kidney injuries by a retrospective study during a period of 17 years. Posttraumatic high blood pressure was found in 17 of 86 cases (19.7%) being managed by conservative therapy, and most of them had a grade I-renal trauma (classification according to Hodges). On the contrary, those with a primary operative therapy i.e. when the kidney could be saved or had to be removed, did not show high blood pressure. The high frequency of late complications after conservative treatment of renal trauma supports the necessity of a more active therapy even in slightly damaged kidney.

Adult↗
PubMed1982

The intrarenal renin-angiotensin-system. An immunocytochemical study on the localization of renin, angiotensinogen, converting enzyme and the angiotensins in the kidney of mouse and rat.

The localization of renin, converting enzyme (CE) and angiotensin II (ANG II) in the kidneys of rats and mice was investigated with immunocytochemical methods. According to the presence and specific intrarenal localization of these components of the renin-angiotensin-system (RAS) our results suggest that in addition to the well known systemic effects of the RAS, there are interactions of its components inside the kidney. These interactions may lead to the generation of an extra portion of ANG II in the renal blood stream with its target cells determined by the localization of CE at the luminal side of well defined endothelial areas. These intrarenal-intravasal reactions may or may not reinforce the action of "systemic" ANG II, generated prerenally. In addition, the existence of true intrarenal-interstitial interactions, with the different components and actions of this intrarenal RAS restricted entirely to the kidney is suggested by our results, particularly the demonstration of ANG II within epitheloid cells and the dissociation of systemic renin and ANG II from their local concentrations in renal hypertensive rats.

Angiotensinogen↗
PubMed1982

Immunoreactive renin and angiotensin II in the afferent glomerular arterioles of rats with hypertension due to unilateral renal artery constriction.

The immunoreactivity for renin and angiotensin II (ANG II) in the ischaemic and non-ischaemic kidney of rats with renovascular hypertension was compared with that of the kidneys of sham operated controls. In addition, the renin concentration of these kidneys and the plasma level of ANG II were determined in hypertensive and control animals. In parallel with the renin concentration of kidney cortex, the immunoreactivity, i.e. the JG-index for renin of the afferent arterioles from the ischaemic kidney was slightly increased, that from the non-ischaemic kidney drastically decreased as compared to control kidneys. Similarly, the JG-index for ANG II was increased in the ischaemic and decreased in the non-ischaemic kidney although the plasma level of ANG II was elevated in the animals with renovascular hypertension. This difference in the immunocytochemically detectable ANG II and especially the decrease of ANG II in the non-ischaemic kidney in spite of elevated plasma ANG II levels is interpreted to result from similar differences in the local (extravascular) formation of ANG II by the intrarenal renin-angiotensin system.

Angiotensin II↗
PubMed1982

The localization of converting enzyme in kidney vessels of the rat.

An antibody against pure rabbit lung converting enzyme (CE) showing cross-reaction with CE from other species was used for immunocytochemical studies in the kidney of rats. Using the indirect labelling PAP-technique, specific immunostaining was found in the endothelial layer of all arteries and arterioles of kidney cortex and in some descending vasa recta. CE-positive reactions were also seen in most glomeruli, the reaction product being confined to only a few capillary loops in connection with the glomerular stalk. A few immunostained capillaries in the cortical labyrinth were suspected to belong to the first ramifications of the efferent arteriole. The bulk of all other of the glomerular and peritubula capillaries as well as all veins of the kidney showed no obvious immunostaining. The functional significance of this specific localization pattern of CE in the endothelium of kidney vessels is discussed with respect to the actions of the systemic and the local, intrarenal renin-angiotensin-system on kidney functions.

Animals↗