Über den Einfluss von Acetylcholin auf das Membranpotential denervierter Rattenzwerchfelle

Summary The membran potential of isolated rat-diaphragms has been measured by means of intracellular micro-electrodes, in order to study changes of the resting potential and of the depolarizing action of acetylcholine after section of the phrenic nerve. Within 80 days after denervation, the membrane potential was found to fall exponentially from 87 mV to 66 mV. The action of acetylcholine, on the other hand, was found to be independent of the duration of denervation: between the 4th and the 80th day of denervation: 10^–5g/ml acetylcholine always caused the membrane potential to fall by an average of the 9 mV.     

Die Wirkung der Sulfationen auf das Membranpotential der isoliert durchströmten Säugetiermuskulatur

Summary Electrical potential measurements of membrane resting and action potentials were made by means of electrolyte-filled glass micro-electrodes on single fibres of the musculus gracilis of the cat using a perfused hind-limb preparationin situ. The release of potassium from muscle and the tension developed by the gastrocnemius muscle were simultaneously recorded. The normal resting potential in our series was 91.7 mV (s.d. ± 6.7 mV). Partial replacement of the chloride by sulfate in the perfusion fluid led to (a) potassium release from the perfused hind-limb, (b) reversible contracture of the gastrocnemius muscle, (c) depression of the membrane resting potential which was proportional to the degree of replacement of chloride by sulfate in the perfusion fluid and (d) to the occurrence of volleys of spontaneous fibrillation potentials some of which had the shape of damped oscillations. These findings are similar to those observed after treatment with veratrine and are interpreted to be due to (1) increase in sodium permeability and (2) disturbance of the Donnan equilibrium for chloride ions.     

Tip potentials in microelectrodes filled by boiling under reduced pressure

Zusammenfassung Glasmikroelektroden, mit 3M KCl-Lösung gefüllt durch Kochen in Wasserstrahlvakuum, zeigen einen Zentralwert für das Potential an der Elektrodenspitze (tip-potential) von –2,5 mV; 75% geben entsprechende Werte niedriger als –5 mV. Lagerung der Elektroden bei 6°C lässt das «tip-potential» mindestens 2 Wochen unverändert, während bei 22 °C sein Zentralwert nach 3–4 Tagen grösser als –5 mV wird.     

The effect of shock on blood oxidation-reduction potential

Oxidation-reduction (redox) potential measurements were made in the blood of rabbits subjected to hemorrhagic shock followed by treatment with a mild oxidizing agent (albumin). Control redox potential reading corrected for pH was –8.8±1.3 millivolts (mV) in arterial blood (A) and –18.0±2.0 mV in venous blood (V). This A-V difference indicated that hydrogen equivalents coming from muscle and other tissues were partially consumed in the lungs. A 20-mV drop on the V and a 13 mV on the A side was seen after shock. This did not fully return to control 2 h after return of the shed blood. Infusion of 2 g of albumin/kg/h raised the V redox potential to control, but it returned to untreated levels when the albumin was discontinued. The reductive load imposed on the animal by shock appeared to be large and not readily reversed by reperfusion or by the quantity of albumin given. Thus, it may be concluded that cellular respiration had not been adequately restored. This reductive load may impede recovery by suppression of cellular respiration and other cell and organ functions.     

Wellenlängen-Diskriminatoren im intrakranialen Pinealorgan vonRana catesbyana

Summary The photosensitivity of the epiphysis cerebri of bullfrogs (Rana catesbyana) was investigated by recording with 3 M-KC1 glasscapillary microelectrodes. Of 65 units isolated from the tractus pinealis 21 were inhibited by short wave lengths and excited by longer wave lengths (chromatic response), 44 units were inhibited by all wave lengths (achromatic responses). Most effective for the excitatory component of the chromatic response was green. The spike amplitude of the chromatic response was 5–15 mV, that of the achromatic response 30–40 mV.     

HCN channels contribute to the intrinsic activity of cochlear pyramidal cells

A hyperpolarization-activated current recorded from the pyramidal cells of the dorsal cochlear nucleus was investigated in the present study by using 150- to 200-m-thick brain slices prepared from 6- to 14-day-old Wistar rats. The pyramidal neurones exhibited a slowly activating inward current on hyperpolarization. The reversal potential of this component was –32 ± 3 mV (mean ± SE, n = 6), while its half-activation voltage was –99 ± 1 mV with a slope factor of 10.9 ± 0.4 mV (n = 27). This current was highly sensitive to the extracellular application of both 1 mM Cs⁺ and 10 M ZD7288. The electrophysiological properties and the pharmacological sensitivity of this current indicated that it corresponded to a hyperpolarization-activated non-specific cationic current (I_h). Our experiments showed that there was a correlation between the availability of the h-current and the spontaneous activity of the pyramidal cells, suggesting that this conductance acts as a pacemaker current in these neurones. Immunocytochemical experiments were also conducted on freshly isolated pyramidal cells to demonstrate the possible subunit composition of the channels responsible for the genesis of the pyramidal h-current. These investigations indicated the presence of HCN1, HCN2 and HCN4 subunits in the pyramidal cells.Received 15 May 2003; received after revision 26 June 2003; accepted 21 July 2003     

Intracellular injection of cAMP and cGMP into snail neurones induces an increase in Na+-conductance

Summary Injection of cAMP and more rarely cGMP into the neurones of the snailHelix pomatia induces an increase in membrane conductance, membrane depolarization and excitation. The effect is theophylline-dependent and has a reversal potential near — 10 mV.     

Technique d'enregistrement de l'activité unitaire du cortex cérébelleux,chez le chat chronique

Summary A technique is described for chronic implantation of movable micro-electrodes in cerebellum of the cat, which is especially adapted for recording unit patterns (Purkinje cells) on the unrestrained animal during a learned motor sequence.     

Response to adrenaline,acetylcholine and change of contraction frequency in early human foetal hearts

Zusammenfassung Adrenalin rief einen positiv chronotropen und inotropen, Acetylcholin einen negativ chronotropen Herzeffekt bei zwei menschlichen Foeten von 30 mm Scheitel-Steiss-Länge hervor. Ein Treppenphänomen wurde in Ventrikelstreifen und stabile Membranpotentiale (–70 mV) in einzelnen Ventrikelzellen nachgewiesen.     

Electrical slow waves in oviductal smooth muscle of the guinea-pig,mouse and the immature baboon

Summary Oviducts of the guinea-pig, mouse and immature baboon show prominent electrical slow waves. In the guinea-pig oviduct they are 40–50 mV in amplitude and have a duration of 1.5 sec in the isthmus. Slow waves in these tissues propagate at a speed of 1–13 mm/sec.Decreased 6th December 1977.Supported by NIH-09339-02 and Rockefeller Foundation. A. T. was a Rockefeller Foundation Fellow. Correspondence to B. J. Hodgson, Dept. Obstetrics and Gynecology, UTHSCSA, San Antonio, Texas 78284.     

Oscillatory after-potentials and triggered-automaticity in mammalian ventricular muscle fibres at high resting potentials

Summary Oscillatory after-potentials and triggered-automaticity were observed in dog ventricular muscle fibres when the fibres were exposed to K⁺-free, high-Ca⁺⁺-solutions after K⁺-free, Ca⁺⁺-free perfusion. They appeared at membrane potentials more negative than –60 mV.     

Nachweis einer physiologischen Spontanaktivität in Einzelfasern des N. opticus der Katze

Summary Spike potentials were recorded with metal micro-electrodes from single fibers in the intracranial part of the cat's optic nerve with the retina left completely intact. All units studied as yet showed a marked spontaneous activity irrespective of differences in their response to light stimuli. The spontaneous activity in the intracranial part of the optic nerve could be suppressed reversibly by increasing the intraocular pressure up to 200 mm Hg. Thus spontaneous activity has been verified as a normal feature of the retina. A spontaneous firing rate of 22±11/s after 1 h dark adaptation was found in altogether 12 well-isolated fiber units.     

The response of frog taste cells (Rana nigromaculata andRana catesbeana)

Zusammenfassung Die Registrierung der Rezeptorpotentiale einzelner Geschmackszellen von Raniden (R. nigromaculata undR. catesbeana) bei Reizung mit 4 Grundgeschmacksarten mittels Glasmikroelektrode ergibt: Ruhepotential der Rezeptorzellen 10–35 mV (innen negativ). Die einzelnen Geschmackszellen antworten auf mehr als 2 Geschmacksarten und zeigen im Hinblick auf ihre Antwortmuster zellcharakteristisches Verhalten.     

In situ observations of spontaneous contractions of the peripheral lymphatic vessels in the rat mesentery: Effects of temperature

Summary By means of an intracellular glass microelectrode, action potential changes were successfully recorded in situ from the endothelial cells of rat mesenteric lymphatics over the temperature range of 27–40°C. The frequency of action potential and the lymphatic contraction rate correlated well with temperature.     

The effects of triaminopyrimidine on the short circuit current and transmembrane potentials of the isolated rat visceral yolk sac in vitro

Summary Intracellular potentials in the cells from 17.5-day old rat visceral yolk sacs were measured by a glass microelectrode. When penetrated from the maternal side, the cells have potentials of about 50.2±1.9 mV (inside negative) which were reduced by increasing the external K⁺ concentration and increased by removing Na⁺ ions from the bathing fluid. Triaminopyrimidine (TAP) which inhibited Na⁺ transport caused a dose-dependent depolarization of the cell membrane. The depolarization was dependent on the presence of extracellular Ca²⁺ ions. It is proposed that TAP may inhibit Na⁺ transport by increasing the intracellular concentration of calcium ions.This work was supported by the University of Hong Kong (grant number 335. 034.5105).Acknowledgment. Triaminopyrimidine was synthesized by Dr. Barbara Roth of the Wellcome Research Laboratories.     

Die Wirkung von Adrenalin auf das Ruhepotential von Myokardfasern des Vorhofs

Summary Dog auricle fibres were impaled by 2 intracellular electrodes. The first electrode measured the effect of adrenaline on the resting potential, and through the second one electrotonic impulses were applied.Adrenaline increases the resting potential by 1–35 mV. The polarisation is higher at a low resting potential and increases with the dose.Small polarisations were not accompanied by a detectable change of the membrane resistance. During higher polarisations, the membrane resistance was reduced to 50%.

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Ausgeführt mit Unterstützung der deutschen Forschungsgemeinschaft.     

Development of the steady potential differences of the eyeball in chick embryos

Résumé Le potentiel D. C. mesuré sur la surface du globe oculaire de l'embryon de poulet croît à partir du 15 ème jour de 0.92±0.21 mV jusqu' à 9.26±0.76 mV au 21 ème jour l'incubation. L'augmentation maximum se situe entre le 17 ème et 18ème jour (2.57 et 6.61 mV). Elle correspond à la mise en jeu de l'appareil visuel afférent. La stabilité du potentiel D. C. du globe oculaire est directement proportionnelle à sa valeut.     

On the production of 12α-hydroxysteroid dehydrogenase fromClostridium group P,strain C48-50 ATCC 29733

Summary The production of 12-hydroxysteroid dehydrogenase ofClostridium group P strain C48-50 was optimized when the organism was grown in the presence of 2% fructose and 0.1% dithiothreitol. It appears that an initial redox potential of less than –160 mV (achieved by autoclaving in the presence of dithiothreitol, dithioerythritol or cysteine) is important in the production of this enzyme.     

Das bioelektrische Potential an der zytoplasmatischen Membran der Granulozyten

Summary The bioelectric potential between the interior of granulocytes taken from whole blood and exudatleucocytes and 2 extracellular media was examined with microelectrode-technique. The order of magnitude amounts to about – 5 mV. The potentials of the cell population are Gaussian distributed.

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Frl. D.Lüders sind wir für die sehr sorgfältig durchgeführten Zellpunktionen und Potentialmessungen sowie für die Herstellung der Mikroelektroden zu grossen Dank verpflichtet.     

Calcium ionophore plus excision induce a large conductance chloride channel in membrane patches of human colon carcinoma cells HT-29cl.19A

In excised inside-out membrane patches of the human colon carcinoma HT-29cl.19A cells a large conductance (373±10 pS) chloride channel was found. Channel activity could only be observed after excision of patches from cells incubated with calcium ionophore. The channel was never observed in cell-attached patches. The channel was strongly voltage dependent, being open only between +30 and –30 mV clamp potentials. The selectivity sequence among anions, deduced from reversal potentials, was I>Br>Cl>F>gluconate. The P_Na/P_Cl was 0.09. Although a similar type of channel, has been described earlier, this is the first report stating its appearance in patches of intestinal epithelial cells requiring the combined action of Ca²⁺ ionophore and excision, suggesting its control by an intracellular compound.