Untersuchungen zur Klärung der Funktion des Reissnerschen Fadens. In-vitro-Bindung von Noradrenalin,Adrenalin und Serotonin

Summary The glycoprotein of Reissner's fibre is able to bind norepinephrine, epinephrine and serotonin. Bound amines can be demonstrated at the RF, even after washing with artificial cerebrospinal fluid for some, hours. It is discussed whether it is a function of the RF to remove substances, for instance biogenic amines, from the cerebrospinal fluid.     

Preliminary observations of a bacteriophage infecting Xenorhabdus luminescens (Enterobacteriaceae)

A bacteriophage infective to Xenorhabdus luminescens, a bacterial symbiont of heterorhabditid nematodes, was recovered from insects that supported poor nematode development. Plaque tests showed the phage particles to be infective only to primary and not secondary colonies of X. luminescens. The phage was not infective to X. nematophilus primaries or secondaries. The bacteriophage particles ranged 80-90 nm in length, with the head ranging from 40 to 50 nm in diameter. Restriction analysis was performed on isolated bacteriophage DNA. This first report of a bacteriophage from Xenorhabdus species has practical implications since it could be detrimental to cultures of Heterorhabditis nematodes that are being produced throughout the world for the biological control of insects.     

Mechanism of ion permeation through calcium channels

Calcium channels carry out vital functions in a wide variety of excitable cells but they also face special challenges. In the medium outside the channel, Ca2+ ions are vastly outnumbered by other ions. Thus, the calcium channel must be extremely selective if it is to allow Ca2+ influx rather than a general cation influx. In fact, calcium channels show a much greater selectivity for Ca2+ than sodium channels do for Na+ despite the high flux that open Ca channels can support. Relatively little is known about the mechanism of ion permeation through Ca channels. Earlier models assumed ion independence or single-ion occupancy. Here we present evidence for a novel hypothesis of ion movement through Ca channels, based on measurements of Ca channel activity at the level of single cells or single channels. Our results indicate that under physiological conditions, the channel is occupied almost continually by one or more Ca2+ ions which, by electrostatic repulsion, guard the channel against permeation by other ions. On the other hand, repulsion between Ca2+ ions allows high throughput rates and tends to prevent saturation with calcium.     

Different modes of Ca channel gating behaviour favoured by dihydropyridine Ca agonists and antagonists

Single cardiac transmembranous Ca channels have three modes of gating behaviour in the absence of drugs, expressed as current records with brief openings (mode 1), with no openings because of channel unavailability (mode 0 or null mode) and with long-lasting openings and very brief closings that appear only rarely (mode 2). The dihydropyridine Ca agonist Bay K 8644 enhances Ca channel current by promoting mode 2, while the Ca antagonists nitrendipine and nimodipine inhibit the current by favouring mode 0.     

Induced dominant lethals in female mice: Effects of triaziquone and phenylbutazone

Zusammenfassung Bei weiblichen Mäusen induzierte Triaziquon unter konventionellen Laboratoriumsbedingungen dominante Letalfaktoren, wenn die Substanz im Pro-Oestrus oder im Oestrus verabreicht wurde. Weniger gut geeignet erwies sich diese Applikation wenige Stunden nach Kopulation, da embryotoxische Wirkungen auftraten. Im Gegensatz zu Triaziquon führte Phenylbutazon — weiblichen Mäusen im Oestrus verabreichtnicht zu dominanten Letaleffekten.     

The chemokinetic effect of serum albumin

Summary Experiments performed by means of time lapse cinematography or the filter technique show that human serum albumin has marked chemokinetic effects on neutrophil cultured in Gey's solution. The average speed of the cells, as well as the proportion of neutrophils showing locomotion, is increased. Enhanced locomotion correlates with decreased attachment to the substratum as determined by morphological and functional criteria.We thank Mrs R. Graf and Miss M. Schuster for technical assistance. This work was supported by the Swiss National Science Fondation.     

The site of binding of injected H3-norepinephrine

Zusammenfassung Tritium-markiertes nor-Epinephrin, welches im Meerschweinchenherzen 4 bis 8 h nach intravenöser Injektion gebunden war, wurde mit der gleichen Geschwindigkeit wie körpereigenes Catecholamin nach Verabreichung von Reserpin freigesetzt. Es kann daher angenommen werden, dass injiziertes nor-Epinephrin sich im Herzen mit der Masse des endogenen Hormons vermischt.