Otmar Wassermann

Drug-Induced Phospholipidoses

This review deals with drug-induced lipidoses and the possible underlying mechanisms. A variety of drugs, widely differing in their main pharmacological actions, but closely resembling each other with respect to particular physiochemical properties, have been found to cause in animals and man cytological alterations that are reminiscent of the inherited lipid-storage diseases of man. Ultrastructurally, the alterations are characterized by multilamellated or crystalloid cytoplasmic inclusions, i.e., residual bodies resulting from an intralysosomal accumulation of polar lipids. Biochemically, some of the most severely affected tissues have been demonstrated to contain increased amounts of phospholipids and of the drug applied. All drugs hitherto found to induce such alterations are cationic amphiphilic (amphipathic) compounds; they possess a highly apolar ring system and a cationic hydrophilic side chain (e.g., triparanol, chloroquine, chlorzyclizine, 4,4′-diethylaminoethoxyhexestrol, chlorphentermine, ipri...

NMR-Studies on the molecular basis of drug-induced phospholipidosis—II. Interaction between several amphiphilic drugs and phospholipids

Abstract NMR binding measurements have been performed in order to analyze the molecular mechanism underlying the drug-induced phospholipidosis. The dependency of the T 2 relaxation rates of the various spin systems of the drug molecules on structure, type of lipid, concentrations of interacting species, and ionic strength has been evaluated. Increasing lipophilicity is correlated with an increase in binding for this type of amphiphilic drugs. The degree of signal broadening is determined by the ratio of drug/lipid concentration. Strong interaction occurs with phospholipids, like phosphatidylcholine or phosphatidylethanolamine, whereas less polar lipids, like diacylglycerole or digalactosyldiglyceride, show no interaction with the drugs. Cholesterol antagonizes the phospholipid/drug interaction.

Inhibition of the actions of carbachol and DFP on guinea pig isolated atria by alkane-bis-ammonium compounds

Abstract In isolated guinea pig atria a number of newly synthesized alkane-bis-ammonium compounds abolish the intoxication induced by diisopropylfluorophosphate. This effect can be related to the antagonistic action of the compounds against acetylcholine and carbachol, respectively. The most powerful agents display pA10-values between 7.0 and 6.0 against carbachol. The mode of action of the alkane-bis-ammonium compounds differs from that of atropine and related substances. The compounds are not competitive antagonists, although they provoke a parallel shift of the dose response curves of carbachol to the right. The hypothesis is put forward that the alkane-bis-ammonium compounds react with side receptors thereby diminishing the accessibility of the acetylcholine receptor for the agonists (“allosteric antagonism”).

Evidence for a dissociation between positive inotropic effect and inhibition of the Na+N+-ATPase by ouabain, cassaine and their alkylating derivatives

An attempt was made to gain further information on the correlation postulated between NaK-ATPase activity and the contractile state of heart muscle. The efficiency of a new alkylating agent, cassic acid mustard (CAM) on contractile force and on the NaK-ATPase was compared with cassaine (C) and ouabain (S). The ED50 valuess obtained in isolated guinea-pig atria were (× 10−7 M): C 0.9, CAM 2.7 and S 1.1; the ID50 values resulting from ATPase inhibition experiments were (× 10−6 M): C 1.0, CAM 24, and S 0.25. Low concentrations of all three drugs stimulated the ATPase activity up to 20%. The time course of stimulation is characterized by a half-life of 5 min at a concentration of 1 × 10−0 M ouabain. A considerable discrepancy exists between the time courses of onset of the positive inotropic effect and the development of enzyme inhibition. This is most obvious in the case of ouabain: a drug concentration of 1 × 10−7 M produces a positive inotropic equilibrium within 30 min, whereas the inhibition of the enzyme still continues after a period of more than 60 min. A positive inotropic effect of 80% can be washed out a half lives of 8.3 min for CAM, 2.8 min for C and 4.4 min for S. In contrast to this ready reversibility of the positive inotropic effect, the enzyme inhibition by S is not reversible and persists for more than 30 min upon dilution of the drug-enzyme complex. The data obtained are consistent with the interpretation, that the Na+K+− ATPase is not the mediator of the positive inotropic action of digitalis and related compounds. It is much more tempting to correlate ATPase inhibition with the toxic effects of these compounds.

Bovine spermatozoa as anin vitro model for studies on the cytotoxicity of chemicals: effects of chlorophenols

The suitability of ejaculated bovine spermatozoa as an in vitro model for the assessment of the cytotoxic potential of chemicals was evaluated using several endpoints: swimming activity, adenine nucleotide content, membrane integrity and oxygen consumption. A series of chlorophenols inhibited sperm motion (motility and velocity) in a concentration-dependent manner. This could be determined quantitatively and reproducibly by means of videomicrography and automatic computer image analysis. The sperm immobilizing potency increased with increasing chlorination and was positively correlated with lipophilicity. Concentrations which reduced the percentage of moving sperm to 50% of controls ranged from 43 µM for pentachlorophenol (PCP) to 1440 µM for 4-monochlorophenol (4-MCP). Determinations of adenine nucleotides and percentages of viable cells revealed qualitative differences between the action of PCP and the lower chlorinated phenols. While the latter decreased the total adenine nucleotide contents and the percentage of unstained cells in parallel to motion inhibition, no such changes occurred after exposure to immobilizing concentrations of PCP. Penta-, tetra- and trichlorinated phenols stimulated cellular respiration, indicating their uncoupling activity, at concentrations lower than those necessary for motion inhibition. The results indicate that bovine spermatozoa may become a useful in vitro model for the toxicological evaluation of chemicals providing quantitative as well as qualitative data.

Action of atropine and some hexane-1.6-bis-ammonium derivatives upon the toxicity of DFP in mice

Abstract The toxicity of diisopropyl-fluorophosphate (DFP) has been determined in mice after pretreatment with atropine and/or some new hexane-bis-ammonium compounds. Atropine only had a protective factor of about 2 in the large dose-range of 0.3 − 10.0 −5 mole/kg. Some of the hexane-bis-ammonium compounds were as active as atropine. The combined pretreatment with atropine and a hexane-bis-ammonium derivative, however, gave a more than additive protection against DFP intoxication. Hexane-bis-(dimethyl-phthalamide-N-propyl-ammonium-bromide) proved the most powerful protective agent. In combination with atropine its protective factor was about 16. The mechanisms underlying the actions of atropine and hexane-bis-ammonium compounds are different.

MAO‐inhibitory properties of anorectic drugs

action. It is unlikely that the mydriasis is produced by an anti-acetylcholine action because thymoxamine readily reversed it and also because norfenfluramine does not reduce acetylcholine-induced contractions of human gastric smooth muscle in concentrations of 1-100 ng ml-l (Francis, personal communication). The time course of mydriasis after oral fenfluramine 40 mg is more closely related to plasma levels of norfenfluramine than fenfluramine (Campbell & Kramer, personal communication), and it is probable, therefore, that fenfluramine-induced mydriasis is produced by norfenfluramine. We thank Servier Laboratories Ltd. for supplying fenfluramine and norfenfluramine eye-drops.

Short-term effects of chlorophenols on the function and viability of primary cultured rat hepatocytes

Primary cultured rat hepatocytes were used as an experimental model to detect adverse effects of five chlorophenols (CP) in vitro (penta-CP, 2,3,4,5,-tetra-CP, 2,4,5,-tri-CP, 2,4-di-CP, and 4-mono-CP). Monolayer cultures were exposed to the test compounds for 1 h, and concentration response curves were established with respect to the effects on phase I and phase II metabolism of 7-ethoxycoumarin (7-EC) and on cellular ATP content. All CP tested inhibited the O-dealkylation of 7-EC, with half-maximum effective concentrations (EC50) ranging from about 36 μM for the three highest chlorinated phenols to 215 μM for 4-mono-CP, which proved to be least effective. The subsequent conjugation of the primary metabolite 7-hydroxycoumarin was even more sensitive towards CP exposure than the O-deethylation process. The concentrations which reduced the percentage of conjugated metabolite to 50% of the respective control cultures ranged from 7 μM for penta-CP to 48 μM for 4-mono-CP. Treatment of cultured hepatocytes with CP additionally resulted in a depletion of cellular ATP at EC50 concentrations ranging from 6 μM for penta-CP to 1330 μM for 4-mono-CP. Cellular viability, as measured by the leakage of lactate dehydrogenase from the cells, was not affected by any of the CP within the 1-h exposure period.

Über eine akute Anti-Acetylcholin-Wirkung von Hemicholinium No. 3 am Vorhof des Meerschweinchens

SummaryInvestigations on the postsynaptic actions of Hemicholinium No. 3 (HC-3) have been carried out in guinea pig isolated atria. Depression of sensitivity to externally applied acetylcholine (ACh) is demonstrated in spontaneously beating preparations.HC-3/ACh-concentration-response curves are supposed to represent a special type of a non-competitive interaction. HC-3 (50 μg/ml) produced an acute and nearly complete blockade to electrical stimulation in isolated vagus-atrium preparations. Similarly HC-3 abolishes the response to selective stimulation of intramural cholinergic nerve terminals. In all cases this acute inhibition was completely reversible.ZusammenfassungDie postsynaptische Wirkung von Hemicholinium No. 3 (HC-3) wurde an isolierten innervierten Vorhöfen von Meerschweinchen untersucht.Die Empfindlichkeit von spontan kontrahierenden Atrien gegen exogenes Acetylcholin ist in Anwesenheit von HC-3 (10–100 μg/ml) verringert. Die Rechtsverschiebung der Konzentrations-Wirkungskurven stellt vermutlich einen speziellen Fall eines nichtkompetitiven Antagonismus dar. An isolierten Vagus-Atrium-Präparaten blockierte HC-3 in einer Konzentration von 50 μg/ml akut und nahezu vollständig die cholinerge Phase der Reizantwort. In ähnlicher Weise hob es den Erfolg einer selektiven Reizung intramuraler cholinerger Nervenfasern auf. Diese akute Hemmung war in jedem Falle voll reversibel.

Studies on the pharmacokinetics of bis-quaternary ammonium compounds

SummaryOn each nitrogen atom of 3H-hexamethonium one methyl group was replaced either by a n-propyl, N-n-propylphthalimide or n-nonyl group. By means of whole-body autoradiography the influence of the different substituents on the distribution pattern was studied in mice after i.v. or s.c. injection. Increasing the chain length of the substituents caused an enhanced accumulation of the respective compounds into secreting tissues, heart muscle, and liver, and an augmentation of biliary excretion. The affinity of the bis-quaternary ammonium compounds for cartilaginous tissues was also altered. The physiological “barriers” between blood and brain or blood and the aqueous humor of the eye, were highly effective against the compounds studied, whereas the placenta could be penetreted by these derivatives.