Zur Ableitung von Demarkationspotentialen und monophasischen Aktionsströmen an der Eingeweidemuskulatur

Zusammenfassung Es wird eine Methode zur Registrierung von Demarkationspotentialen am glatten Muskel beschrieben, die es gestattet, in dem Zeitraum von etwa 1/2 Std laufend die relativen Änderungen des Membranpotentials zu verfolgen und monophasische Aktionsströme aufzuzeichnen. Gleichzeitige Registrierung der Muskelmechanik ist möglich.Mit 5 Textabbildungen     

A micropuncture study of the effect of isoprenaline on renal tubular fluid and electrolyte transport in the rat

Summary To explain the mechanism of the isoprenaline induced antidiuresis the effect of this substance on fluid and electrolyte reabsorption in various nephron segments of the rat kidney has been studied using micropuncture techniques. Isoprenaline (1.5×10^–9 mol/kg·min i.v.) decreased GFR of superficial nephrons and increased fractional proximal fluid, sodium and potassium reabsorption. However, the fractions of filtered fluid and electrolytes, which had been reabsorbed up to the early distal tubule were unchanged after isoprenaline. This indicates that the increased fractional proximal reabsorption has been completely compensated by decreased reabsorption from Henle's loops. In the distal convoluted tubules an increase in the fractional fluid and sodium reabsorption could be established using a recollection technique. Given directly into the distal tubular lumen isoprenaline stimulated the isotonic fluid reabsorption, which was measured by the Gertz split oil droplet method.From these results it is concluded that the decrease in superficial GFR and the increased distal tubular fluid and sodium reabsorption lead to the decrease in urine volume and in urinary electrolyte excretion after isoprenaline.with the technical assistance of U. Greven and S. HildebrandSupported by Deutsche ForschungsgemeinschaftPortions of this work were presented at the Meeting of the Deutsche Pharmakologische Gesellschaft in Graz, 1974 (Greven, 1974b)     

The dentition of European Speleomantes spp. (Urodela, Plethodontidae) with special regard to sexual dimorphism.

Dentigerous bones and dentition of juveniles and adults of several European Speleomantes-species were investigated using scanning electron microscopy. In the juveniles examined, all dentigerous bones bore bicuspid teeth. The adult males showed the well-known dentitional sexual dimorphism, i.e. monocuspid largely conical, elongated and strongly curved premaxillary teeth. However, teeth of the anterior portion of the maxillae and some teeth of the dentary were also clearly monocuspid; the remaining teeth had differently shaped apices considered to be different grades of bicuspidity. Vomerine teeth were exclusively bicuspid. Monocuspid, but smaller teeth were also found on the premaxilla of an adult female. The conical monocuspid tooth in adults is a modified metamorphosed tooth. Monocuspids, at least on the premaxillae, may be constantly present in males and development of monocuspids probably depends on differential sensitivities of the tooth producing tissue for androgen stimuli.     

Effects of the alpha 2-adrenoceptor antagonists yohimbine and idazoxan on kidney function in intact and diabetes insipidus rats

The purpose of the present study was to examine the effect of the alpha 2-adrenoceptor antagonists yohimbine and idazoxan on kidney function in intact Sprague-Dawley rats and in Brattleboro rats with familial hypothalamic diabetes insipidus. Both drugs, injected intravenously at 0.5 mg/kg, led to a marked decrease of urine flow, sodium, potassium and chloride excretion in both strains of rats. Glomerular filtration rate and effective renal plasma flow did not change significantly in either strain. The study demonstrates that the alpha 2-adrenoceptor antagonists induce an antidiuretic effect without changes in renal hemodynamics. Antidiuretic hormone does not play a role in yohimbine- or idazoxan-induced antidiuresis. The data suggest a role for alpha 2-adrenoceptors in the renal tubular handling of water and salt.     

Evidence for redistribution of filtrate among nephrons after beta-adrenergic stimulation and blockade

Summary Renal excretion of fluid and electrolytes, total kidney GFR and superficial nephron GFR were determined in 42 Sprague Dawley rats after beta-adrenergic stimulation with isoprenaline and beta-adrenergic blockade with propranolol. Isoprenaline (0.3 g/kg · min i. v.) decreased urine volume, sodium and potassium excretion and increased urinary sodium and potassium concentration and urine osmolarity. These effects were reversed by injection of propranolol (2.2 mg/kg i.v.). Propranolol alone increased renal sodium and potassium excretion and urinary sodium concentration. Total kidney GFR did not change after both substances, whereas superficial nephron GFR increased after propranolol by 35% and decreased after isoprenaline by 35%. A redistribution of glomerular filtration rates among nephrons therefore must have occured with a shift of the GFR to deep nephrons after isoprenaline and to superficial nephrons after propranolol. The redistribution of glomerular filtration rates is thought to the related to the changes in urinary excretion of electrolytes. Additionally, isoprenaline increased fractional fluid reabsorption of superficial proximal convoluted tubules by 12.3%.     

Dissociation of the behavioural and endocrine effects of lysine vasopressin by tryptic digestion

1. Lysine vasopressin induces resistance to extinction of active avoidance behaviour (De Wied, 1971).2. Digestion of lysine vasopressin with trypsin almost completely destroys the pressor-, antidiuretic-, oxytocic- and corticotrophin-releasing factor activities of lysine vasopressin, but does not materially influence its effect on the maintenance of an avoidance response.     

Asbestos-related diseases in the federal Republic of Germany

Until recently, in the Federal Republic of Germany there has been a lack of epidemiological data on asbestos-related tumors. Only the numbers of occupational diseases accepted for compensation by the German industrial injuries insurance institutes (Berufsgenossenschaften) can be stated. These show, for 1979, 94 cases of asbestosis, 21 cases of asbestosis associated with lung cancer, and 34 cases of mesothelioma. Since 1972 employees exposed to asbestos dust have been included in a central register by the industrial injuries insurance institutes and are medically examined periodically. By December 31, 1979, 28,476 persons were registered. Of those, 6,582 were still being followed medically, although they were no longer working with asbestos dust exposure. In January 1, 1977, a prospective epidemiological study was started with these people who were formerly exposed to asbestos dust. Up to December 31, 1980, altogether 2,944 people were enrolled in the study. Besides several other enrollment criteria, the individual's permission was required to evaluate his personal data. Of the people enrolled, 85 had died by December 31, 1980. Even if five questionable cases of lung cancer are excluded (n = 80), the observed rates of about 43% tumours of all sites, with 15% lung cancer and 6% mesothelioma, seem to be comparable to the international epidemiological mortality pattern.