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C Alsen

Publications and source records attributed to C Alsen.

14 recordsLinked to original sources
PubMed1983

Biological significance of peptides from Anemonia sulcata.

Three polypeptide toxins have been isolated from the sea anemone Anemonia sulcata and characterized: ATX I (mol wt 4702), ATX II (mol wt 4935), and ATX II (mol wt 2678). In different crustacean and amphibian preparations the toxins act primarily on the fast sodium channels, which leads to delayed inactivation of fast sodium permeability and thus increases the duration of the action potential. When applied to crustacean preparations the three toxins are nearly equally effective. However, in a comparison of the biological activities of ATX I and ATX II in myelinated nerves of the frog, ATX I seems to be inactive. It is suggested that cardiotoxicity is the primary cause of death in mammals, ATX II being more toxic than ATX I. At very low concentrations ATX II induces a pronounced positive inotropic effect in different mammalian heart preparations, which is accompanied by a prolongation of the action potential. It is suggested that the positive inotropic effect of ATX II is caused by a delayed inactivation of the fast sodium current, which leads to an increase of the sodium transient and of the pump activity of Na+,K+-ATPase. In contrast to the presynaptic mode of action on crustacean and frog nerve-muscle preparations, ATX II has a direct effect on mammalian skeletal muscle fiber membranes and induces a sodium-dependent increase of twitch responses and duration of the action potential.

Amino Acid Sequence↗
PubMed1981

Mechanical and electrophysiological effects of sea anemone (Anemonia sulcata) toxins on rat innervated and denervated skeletal muscle.

1 Some effects of the sea-anemone toxin ATX-II on mammalian nerve-muscle preparations have been described. 2 When ATX-II (10(-8)-10(-6) M) was applied to rat hemidiaphragm preparations, both directly and indirectly generated twitch responses were potentiated and prolonged. At the same time the resting tension of the preparations increased. 3 The increase in resting tension caused by ATX-II in innervated muscles was not prevented by curarization, but was reversed by exposure to tetrodotoxin. The increase in denervated muscles was not completely reversed by tetrodotoxin. 4 At concentrations exceeding 1 x 10(-7) M, ATX-II caused a sodium-dependent depolarization of both normal and denervated muscles. The depolarization of the denervated muscles was only partially reversed by tetrodotoxin. 5 In the presence of ATX-II repetitive endplate potentials (e.p.ps) were evoked by single shocks to the motor nerves in many fibres, and in those in which a single e.p.p. was still observed, the quantum content (m) was increased. Miniature e.p.p. frequency was not increased by ATX-II, even when muscle fibres were depolarized by 30 mV. 6 The indirectly and directly elicited action potentials of normal and denervated muscle fibres were much prolonged by ATX-II. The action potentials remained sodium-dependent. The sodium-dependent tetrodotoxin-resistant action potential of the denervated muscle fibre was also prolonged by ATX-II. 7 It is concluded that ATX-II both activates, and delays inactivation of, sodium channels in mammalian skeletal muscle fibres, probably in interacting with the channel "gate'.

Action Potentials↗
PubMed1976

Effects of cadmium on carbonic anhydrase activity and hemoglobin content of rat testes.

The cadmilm-induced (Cd) damage of mammalian testes is thought to be correlated with an inhibition of carbonic anhydrase (CAH) by Cd. Since Cd causes dose-dependent changes in blood flow of the testes, an inhibition of CAH in the testes could be simulated by a decrease of CAH-rich erythrocytes. Therefore, CAH activities and hemoglobin (Hb) content were determined in blood and testes of untreated and Cd-treated Sprague-Dawley rats as well as in testes perfused via the testicular artery. Cd was intraperitoneally applied as CdCl2 in single doses of 1.5, 3.0, and 5.0 mg Cd2+/kg b.w., respectively. 1. The experiments on perfused testes clearly demonstrated that the CAH activities originate from erythrocytes rather than from a tissue located enzyme. 2. The alterations in blood circulation occurring shortly (0.25-1.0 h) after the Cd administration were characterized by a dose-dependent, transient decrease (1.5 mg Cd2+/kg) as well as an increase (3.0 and 5.0 mg Ck2+, respectively) of the Hb content in the testes. 3. Independent of these minor alterations in a later state (14-24 h after 1.5 mg Ck2+/kg, 7-14 h after 3.0 mg Cd2+/kg, and 1-3 after 5.0 mg Cd2+/kg), Cd induced the well known hemorrhagic alterations of the testes with a high increase of Hb content and CAH activity. 4. By means of the correlations between CAH activities and Hb content in blood and testes an inhibition of the CAH by Cd as the primary cause for the tissue damage of the testes could largely be excluded.

Animals↗
PubMed1976

The action of a toxin from the sea anemone Anemonia sulcata upon Mammalian heart muscles.

The cardiac activity of toxin II, a basic polypeptide (m.w.: 4770) from the sea anemone Anemonia sulcata, was investigated in isolated electrically driven guinea-pig and rat auricles, Langendorff heart preparations of guinea-pigs and cat heart-lung preparations. Low concentrations of toxin II (2-100 nM) evoked a dose-dependent positive inotropic effect in the three different heart muscle preparations investigated. Higher concentrations of toxin II produced toxic symptoms like contracture and arrhythmia in auricles and atria (about 25 nM). In isolated cat hearts high toxin II concentrations (about 160 nM) caused unusual toxic symptoms such as long periods of ventricular fibrillation alternating with periods of normal cardiac activity. In rat and guinea-pig auricles as well as in Langendorff hearts of guinea-pigs the extent and rate of the positive inotropic effect induced by toxin II depended on the extracellular calcium concentration (0.45 to 2.7 mM). Toxin II did not alter the heart rate in spontaneously beating isolated cat hearts. In electrically driven guinea-pig auricles, the rate of the inotropic effect induced by toxin II was accelerated by increasing stimulation frequencies. Toxin II did not change the coronary flow in Langendorff heart preparations of guinea-pigs.

Animals↗
PubMedDate not supplied

Studies on the mechanism of the positive inotropic effect of ATX II (Anemonia sulcata) on isolated guinea pig atria.

The basic polypeptide ATX II (MW 4,770) isolated from the sea anemone Anemonia sulcata evokes a pronounced and dose-dependent positive inotropic effect in different mammalian heart preparations. The mechanism of this effect is so far unknown. (a) Investigations on isolated guinea pig atria indicate that changes of the steady state cellular Na, K and Ca concentrations cannot account for the positive inotropic effect. (b) An increase of the surface pressure of phospholipid monolayers was observed only at cardiotoxic ATX II concentrations. However, the 45Ca binding to phosphatidylserine, as the essential Ca-binding phospholipid, was not changed even at cardiotoxic ATX II concentrations. (c) Neither the enzymatic activity nor the ouabain inhibition kinetic of an isolated Na/K-ATPase preparation was affected by ATX II. (d) In intact electrically stimulated (1 Hz) guinea pig atria the binding of [3H]ouabain increases by about 50% at a positive inotropic ATX II concentration. The results suggest that the positive inotropic effect of ATX II is not caused by an unspecific membrane damaging action or by a direct interaction with the Na/K-ATPase. The increased binding of [3H]ouabain to intact heart muscles indirectly reflects an increased pump activity of the Na/K-ATPase, which is caused by an elevated Na transient due to the electrophysiologically well-established mechanism of the ATX II action on fast Na channel, i.e., delayed inactivation of the fast Na flux. However, the exact mechanism of the ATX II induced positive inotropic effect remains unknown.

Animals↗
PubMedDate not supplied

Distribution of gold in serum erythrocytes and white blood cells after in vitro incubation and during chrysotherapy with different gold compounds.

We examined the binding of gold to serum proteins and the gold level in serum and in blood cells both after incubation in vitro and under longterm treatment with 3 gold compounds. Gold was measured by atomic absorption spectrophotometry, a serum fractionated by gel chromatography; blood cells were separated by gradient centrifugation, and intracellular gold was measured after pressure decomposition and MIBK-extraction. Aurothiomalate (GSTM), gold keratinate (GK), and auranofin (AF) were used. AF showed the highest binding to globulins in in vitro and in vivo. With GSTM and GK there were no measurable amounts of gold in the red cell lysate or erythrocyte membranes whereas with AF 40% of gold was localized within erythrocytes. The amount of gold in granulocytes and mononuclear cells after incubation with AF is considerably higher than with GK and GSTM.

Auranofin↗