Effect of adrenergic blockade with bretylium and phentolamine on glomerular filtration rate in the rainbow trout, Salmo gairdneri Rich., adapting to saline water

In resting conscious trout, Salmo gairdneri, a gradual increase in external salinity (brackish water) resulted in an immediate decline of glomerular filtration rate and urine flow. These renal responses were partly blocked by the administration of bretylium and phentolamine. The presence of adrenergic nerve endings in the trout kidney and these pharmacological results together provide evidence of neural control of renal haemodynamics. The action of vasoactive substances and innervation is discussed briefly in relation to their importance for normal renal function.

Oxidative enzymes in the urinary apparatus of several marine fishes

The distribution and activities of several oxidative enzymes in the urinary apparatus of seven marine fish species (hagfish, lesser spotted dogfish, electric ray, herring, marine catfish, cod, sea-horse) have been studied. Species were selected from three main taxonomic groups: Cyclostomata, Elasmobranchii and Teleostei. Distinctly positive enzyme reactions were found in the tubular elements of the kidney and the collecting duct-archinephric duct system, with the exception of the generally weak staining intensities for NADP-linked malate dehydrogenase. In the proximal tubule segment the second, ore distal part (PII) reacted, in general, very strongly when compared with the first proximal part (PI). If present, the distal tubule in teleosts showed only weak reactions, while this segment in elasmobranchs exhibited moderate to strong enzyme activities. In the epithelial cells of the collecting tubule-collecting duct system stronger reactions were confined to the glomerular teleost species, the corresponding part of the elasmobranch kidney showing weak staining intensities. In the urinary duct system distinctly positive enzyme reactions were only to be found in the archinephric duct of the teleost species, except for Plotosus. The ureters of the elasmobranchs exhibited weak enzymes activities throughout. The enzyme patterns of the various types of urinary tubules and ducts are compared with observations from several morphological and physiological studies. The histochemical findings are discussed in relation to corresponding investigations of freshwater fishes and problems arising from phylogenetic divergence of marine fish groups.

The glomerulus of a stenohaline fresh-water teleost, Carassius auratus gibelio, adapted to saline water. A scanning and transmission electron-microscopic study

Prussian carp, Carassius auratus gibelio, were maintained in aquaria with a salinity of 15 0/00 for 3 months. More than 90% of the glomeruli disappeared from the tissue as a result of the adaptation to saline water. Kidney tissue was excised and prepared for electron microscopy after perfusion fixation in situ. The fine structure of the renal corpuscle was compared with the normal ultrastructure of glomeruli of control fish from fresh-water aquaria. The main alterations include retraction of the endothelium from the basement membrane, widening of the subendothelial region, folding of the thickened basement membrane and epithelial layer, and the dislocation of slit diaphragms. The findings are discussed in relation to developmental stages of mammalian glomeruli and glomeruli from tissue cultures. The structural changes of the rudimentary glomeruli of the carp kept in 15 0/00 salt water differ from those observed in euryhaline fish from sea water.

The use of proteases as thrombolytic agents from the toxicological point of view

In case of systematic hyperproteolysis in the blood of experimental animals after application of ocrase, a fibrinolytically active protease from Aspergillus ochraceus, toxic side effects, particularly on hemostatis and cardiac action, were observed. In order to prevent toxic effects, ocrase in thrombolytic therapy is to be administered within the inhibitor level. After daily administration of 5.6 mg/kg of ocrase (50% of inhibitor level) to rats, toxicological examinations over four weeks showed no deviation from the regular hematological and biochemical values. The thrombolytic effect of ocrase is explained by the formation of an inhibitor-ocrase complex which acts thrombolytically in the presence of fibrin.

Oxidative enzymes in the urinary apparatus of several freshwater fishes

The distribution and activities of several oxidative enzymes in the urinary apparatus of five freshwater fish species (river lamprey, lobe finned eel, Prussian carp, rainbow trout and three-spined stickleback) have been studied. Species were selected from three main taxonomic groups: Cyclostomata, Polypterini, Teleostei. Distinctly positive enzyme reactions were only found in the tubular elements of the kidney and the collecting duct-archinephric duct system, with the exception of the generally weak staining intensities of lactate dehydrogenase. The distal tubule normally showed strong to very strong reactions for most of the enzymes investigated. In the epithelial cells of the collecting tubule-collecting duct system, stronger reactions were observed for most of the mitochondrial-bound enzymes, especially succinate dehydrogenase and NADH-diaphorase. For these enzymes, the cells of the archinephric duct reacted strongly positive in Lampetra, Carassius and Gasterosteus. The enzyme patterns of various types of urinary tubules and ducts are compared with results of several morphological studies. In addition, the histochemical findings are discussed in relation to kidney function in different vertebrate groups.

The kidney of a teleost, Spinachia spinachia. II. Histochemical identification of sialic acid-containing glycoprotein and fine structure of mucus secreting cells

Kidney cells of the marine stickleback Spinachia have been studied with histochemical methods for the demonstration of glycoconjugates. The fine structure of epithelial cells is described. Mucus threads in the nephronic tubule of sexually mature consist of neutral glycoprotein which corresponds with the secretory granules in proximal tubule segment II cells. Large lysosome-like inclusions, which also react with PAS, are present in many P II cells. All cells of the collecting duct epithelium differentiate into mucous cells in male Spinachia. The nature of their secretory products, which are well preserved by freeze-drying, is discussed. Sialylated glycoprotein is present in mucus granules and sulphated glycoprotein can be demonstrated at the apex of collecting duct cells. Collecting duct cell mucus can be digested with testicular hyaluronidase indicating that proteoglycans may be involved in the structure of macromolecules. The observations are compared with studies of mucus production in the urinary apparatus of several other vertebrates.

The kidney of the prussian carp, Carassius auratus gibelio (Cyprinidae). III. Glycogen-rich cells in the distal segment of nephronic tubule

Glycogen may be present in considerable amount in the distal segment of the nephronic tubule of a teleost freshwater fish, as revealed by light- and electron-microscopical observation. Adaptation of Crassiss auratus gibelio to increased salinity causes alterations of the cell fine structure (e.g. mitochondria and baso-lateral infoldings) but apparently does not influence deposition of glycogen. However glycogen storage is directly controlled by environmental temperature and may be part of an annual rhythm in carbohydrate metabolism.