1. Compound II is a novel analogue of sotalol which has been reported to be free of beta-adrenoceptor and L-type calcium channel blocking actions. The effects of compound II on the contraction of guinea-pig papillary muscles (at 2 microM) and single ventricular myocytes (at 100 nM) were investigated. 2. Exposure to compound II caused a significant increase in the contraction of both preparations. 3. Compound II prolonged the action potential of the single myocytes and increased the magnitude of the Ca-activated current which was used as a qualitative indicator of the intracellular calcium transient. 4. The ratio of first/steady state Ca-activated currents evoked by short action potentials was not modified. This may indicate that compound II does not influence the normal functioning of the sarcoplasmic reticulum stores. 5. The observations are consistent with the hypothesis that action potential prolongation by compound II reduces Ca2+ extrusion via the Na-Ca exchange. This in turn allows increased uptake of calcium into the sarcoplasmic reticulum stores so that more calcium is available for release by subsequent action potentials, leading to an increase in intracellular calcium transients and contractions.

1 The actions and mechanisms of action of novel analogues of sotalol which prolong cardiac action potentials were investigated in guinea-pig and rabbit isolated ventricular cells.2 In guinea-pig and rabbit cells the compounds significantly prolonged action potential duration at 20% and 90% repolarization levels without affecting resting membrane potential. In guinea-pig but not rabbit cells there was an increase in action potential amplitude and in rabbit cells there was no change in the shape or position of the 'notch' in the action potential.3 Possible mechanisms of action were studied in more detail in the case of compound II (1-(4-methanesulphonamidophenoxy)-3-(N-methyl 3,4 dichlorophenylethylamino)-2-propanol). Prolongation of action potential duration continued to occur in the presence of nisoldipine, and calcium currents recorded under voltage-clamp conditions were not reduced by compound II (1-mu-M). Action potential prolongation by compound II was also unaffected in the presence of 10-mu-M tetrodotoxin.4 Compound II (1-mu-M) did not influence I(K1) assessed from the current during ramp changes in membrane potential (20 mV s-1) over the range -90 to -10 mV.5 Compound II (1-mu-M) blocked time-dependent delayed rectifier potassium current (I(K)) activated by step depolarizations and recorded as an outward tail following repolarization. When a submaximal concentration (50 nM) was applied there was no change in the apparent reversal potential of I(K).6 Submaximal concentrations of compound II were without effect on activation of I(K) with time at a membrane potential of + 40 mV, and no changes were detected in the time constants of the two components of I(K) decay over the range of potentials - 60 to 0 mV. Compound II (50 nM) appeared to cause a small shift in the activation of I(K) with membrane potential (an apparent shift of approximately 10 mV in the depolarizing direction at the mid-point of the curve).7 Log dose-response curves for action potential prolongation and for blockade of I(K) by compound II were similar. The IC50 for compound II was approximately 30 nM.8 It is concluded that this novel series of compounds prolongs action potential duration, and that in the case of compound II the evidence supports a potent selective effect on the time-dependent potassium current I(K), an effect which can account for this prolongation.

The major in vivo metabolites of (--)-delta 7-tetrahydrocannabinol were extracted from the livers of mice after a single intraperitoneal dose and were examined by combined gas-liquid chromatography-mass spectrometry. Twenty-six metabolites were identified; most of these appeared to be produced via epoxidation of the double bond, although the epoxides themselves were not detected. Major metabolites involved hydroxylation of the double bond, to give the isomeric 1 alpha- and 1 beta, 7-dihydroxyhexahydrocannabinols. Of these, the 1 alpha, 7-isomer was the major product and appeared to be produced by hydrolysis of 1 alpha, 7-epoxyhexahydrocannabinol. It was further oxidized to 1 alpha-hydroxyhexahydrocannabinol-7-oic acid. Rearrangement of the epoxide to the 7-aldehyde and subsequent reduction to either the 7-alcohol or oxidation to the 7-acid was another major metabolic route. Derivatives of all these metabolites, hydroxylated in the 2"-, 3"- and 4"-positions of the sidechain were also identified. Allylic hydroxylation, predominantly at position 6, was also observed, but this was a relatively minor route. Reduction of the double bond yielded the isomeric axial and equatorial hexahydrocannabinols in low yield.

Annals of the New York Academy of SciencesVolume 281, Issue 1 p. 151-161 THE EFFECTS OF CANNABINOIDS AND OTHER CNS DEPRESSANTS ON CELL MEMBRANE MODELS E. W. Gill, E. W. Gill Department of Pharmacology, Oxford University, Oxford OX1 3QT, EnglandSearch for more papers by this author E. W. Gill, E. W. Gill Department of Pharmacology, Oxford University, Oxford OX1 3QT, EnglandSearch for more papers by this author First published: December 1976 https://doi.org/10.1111/j.1749-6632.1976.tb27927.xCitations: 10AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume281, Issue1Interactions of Drugs of AbuseDecember 1976Pages 151-161 RelatedInformation

The effects of (-)- and (+)-Δ 1 -tetrahydrocannabinol (Δ 1 -THC), the dimethylheptyl analogue of (-)-Δ 1 -THC, 7-hydroxy-Δ 1 -THC, cannabinol, and cannabidiol on the molecular mobility of the hydrocarbon phase of lecithin/cholesterol ultrasonically dispersed vesicles (liposomes) were investigated using a nitroxide-labeled dipalmitoyllecithin as a molecular probe. At low concentrations (-)-Δ 1 -THC fluidized the lipid bilayer; at Δ 1 -THC to lecithin ratios greater than 0.05:1 the effect leveled off and the change in the order parameter remained constant and independent of the membrane concentration. The maximum increase in bilayer fluidity produced by Δ 1 -THC was considerably less than that produced by general anesthetics at membrane concentrations corresponding to those producing anesthesia in vivo . (+)-Δ 1 -THC (the "unnatural" optical isomer of Δ 1 -THC) was less effective than (-)-Δ 1 -THC, whereas the dimethylheptyl analogue and 7-hydroxy-Δ 1 -THC were more effective. Hence ability, at low concentrations, to disorder liposome bilayers correlates well with psychoactive potency. Cannabinol and cannabidiol decreased the fluidity of the liposome bilayer. Octanol, a potent general anesthetic, fluidized lipid bilayers; hexadecanol and tetradecane (which do not produce anesthesia in vivo ) were less effective than Δ 1 -THC in fluidizing liposomes and, at high doses, produced a cannabis-like cataleptic state in mice. It is suggested that the psychoactive cannabinoids may be classified as "partial anesthetics," producing a perturbation of the membrane structure qualitatively similar to that produced by subanesthetic doses of general anesthetics, but which, because of their limited solubility in the lipid phase of cell membranes, are unable to produce the degree of membrane disorder corresponding to clinical anesthesia.

The effects of a range of steroids related to a potent intravenous anesthetic, 3α-hydroxy-5α-pregnane-11,20-dione, on the molecular mobility and local polarity of ultrasonically dispersed vesicles of lecithin and cholesterol (liposomes) were investigated using a nitroxide-labeled dipalmitoyllecithin as a molecular probe. The anesthetics 3α-hydroxy-5α-pregnane-11,20-dione, 3α-hydroxy-5α-pregnan-20-one, butobarbitone, and octanol were found to cause fluidization of the lipid bilayer at concentrations approximating those attained during anesthesia in vivo, and the magnitude of the effect was linearly related to the drug concentration. When allowance was made for differences in molecular volume, it was found that these four molecules produced a degree of fluidization approximately the same as that found previously to be produced by halothane, at a given partial volume of drug in the liposomes. On the other hand, the steroids 3β-hydroxy-5α-pregnane-11,20-dione, 3β-hydroxy-5α-pregnan-20-one, 3α-hydroxy-5α-pregn-16-ene-11, 20-dione, and 3α,11α-dihydroxy-20,20-ethylenedioxy-5α-pregnane, which are inactive as anesthetics, produced much less disordering of the lipid bilayer. The correlation of anesthetic potency with ability to disorder spin-labeled liposomes suggests the use of this technique for drug screening. The especially large difference between the effects of the 3α- and 3β-hydroxy isomers of 5α-pregnane-11,20-dione showed that phospholipid/ cholesterol bilayers are capable of a high degree of structural discrimination, and lends support to the hypothesis that the lipid phase of nerve cell membranes is the site of action of all general anesthetics.

The tritium-labelled unnatural enantiomorph of Δ1-tetrahydrocannabinol(Δ1-THC) was synthesized. The 3H-(+)-Δ1-THC had a specific activity of 1.3 Ci/mmole and an optical purity of ca. 97%. The equipotent molar ratio for (+) and (−)-Δ1-tetrahydrocannabinols was determined in mice by an established behavioural bioassay. The (+)-Δ1-THC was found to be significantly less potent than the laevorotatory isomer, the mean potency ratio being 13 (95 per cent confidence limits: 7 and 24). Brain levels of (+)-Δ1-THC and its metabolites were measured in mice 20 min after intravenous injection of 3H-(+)-Δ1-THC (2 mg.kg) and were compared with the corresponding levels of (−)-Δ1-THC and its metabolites. With the exception of the concentrations of one metabolite, no statistically significant differences were observed between the mean levels of enantiomorphs of the cannabinoids in the brain. In the case of the single metabolite (which was tentatively assigned the structure of 7-hydroxy-Δ1-THC) the brain level of the dextrorotatory isomer was 1.8-times higher than that of the laevorotatory isomer, a difference which was statistically significant. On incubation in vitro with an enriched mouse liver homogenate, (+)-Δ1-THC was partially metabolized to more polar compounds; the principal metabolite was shown to be (+)-7-hydroxy-Δ1-THC. It was concluded that the differences in the psychopharmacological potencies in vivo of the optical isomers of Δ1-THC are determined within the central nervous system and are not due to gross differences in metabolism or body distribution.

Unlabelled and tritium-labelled (sp. act. 373 mCi/m-mole) forms of the 1,2-dimethylheptyl analogue of Δ1-tetrahydrocannabinol (Δ1-DMHP) were prepared as incompletely separated mixtures of threo- and erythro-isomers. The n-heptyl analogue (n-hep-tyl-Δ1-THC), was also prepared, and this compound, and samples of Δ1-DMHP containing different proportions of threo- and erythro-isomers. were compared with Δ1-THC using the mouse ring “catalepsy” test. n-Heptyl-Δ1-THC was found to be twice as active as Δ1-THC (95 per cent confidence limits 1 and 3): the two isomers of Δ1-DMHP were shown, within the limits of the assay, to possess equal activity, giving a mean potency ratio of 12. The duration of action of both drugs did not differ from that of Δ1-THC. Brain and blood levels of Δ1-DMHP and its metabolites were measured at various times after injection with 3H-Δ1-DMHP (0.1 mg/kg) and were compared with the corresponCling levels of Δ1-THC and its metabolites. The major metabolite in the mouse of Δ1-DMHP was isolated from an in vitro mouse liver preparation, and was identified as 7-hydroxy-Δ1-DMHP. The brain levels of this metabolite and Δ1-DMHP itself correlated equally well with the behavioural effect, and showed that the higher activity of Δ1-DMHP is not due to metabolic or distribution effects, as both the amount of 7-hydroxy metabolite relative to the parent, and that, in spite of its greater lipid solubility, the fraction of the injected dose which reached the brain were lower than for Δ1-THC. It was concluded that the differences in the potencies of Δ1-THC and Δ1-DMHP in producing behavioural changes in the mouse are due to differences in activity at the site of action.

Abstract Δ1-Tetrahydrocannabinol (Δ1-THC) and 7-hydroxy-Δ1-THC were injected into the cerebral ventricles of mice by an improved technique, and the potencies of the drugs were measured by the mouse catalepsy test. Both drugs were found to have the same activity when administered by this route as after intravenous injection. Autoradiographic experiments with tritium-labelled compounds showed that at the time of the peak behavioural effect almost all the injected dose of 3H-Δ1-THC (1.6 mg kg−1) or 3H-7-hydroxy-Δ1-THC (0.6 mg kg−1) remained in the intraventricular space and had not penetrated the brain tissue. Δ1-THC was found to remain in the ventricles after the behavioural effect had disappeared; 3% of the injected dose was still present 2 days after injection of 3H-Δ1-THC (1.6 mg kg−1).

Tritium-labelled 7-hydroxy-Δ1-tetrahydrocannabinol (3H-7-hydroxy-Δ1-THC, specific activity 571 Ci/mmole) was prepared from 3H-Δ1-THC by oxidation with a rat liver microsome preparation. Brain levels of 7-hydroxy-Δ1-THC and Δ1-THC in mice were measured 20 min after intravenous injection of either Δ1-THC (2.0, 1.0 and 0.5 mg/kg) or 7-hydroxy-Δ1-THC (1.0, 0.5 and 0.25 mg/kg) and correlated with the inhibition of spontaneous motor activity. A theoretical dose-response relationship for Δ1-THC in the absence of the metabolite was derived on the assumption of additivity of the behavioural effects due to Δ1THC and 7-hydroxy-Δ1-THC present together in the mouse brain. The theoretical dose-response line for Δ1THC and that obtained experimentally for 7-hydroxy-Δ1-THC were parallel; on the basis of brain concentrations, 7-hydroxy-Δ1-THC was found to be more potent than Δ1-THC in producing behavioural changes and the calculated equipotent molar ratio was 7.1. The ratio of the concentrations of Δ1THC and 7-hydroxy-Δ1-THC in the mouse brain 20 min after intravenous injection of Δ1-THC was 5.3 and the contribution of the metabolite to the overall behavioural effect was calculated as 55–63 per cent. Although metabolites of 7-hydroxyΔ1-THC accounted for only about 10 per cent of the radioactivity present in the mouse brain 20 min after intravenous injection of 3H-7-hydroxy-Δ1-THC, about 50 per cent of the radioactivity in the blood was present as a chromatographically more mobile material which has not yet been identified.

Brain levels of Δ1-tetrahydrocannabinol (Δ1-THC) and its major metabolite (7-hydroxy-Δ1-THC) following intravenous injection of tritium-labelled Δ1-THC into mice were measured and correlated with inhibition of spontaneous motor activity. Metabolism of Δ1-THC to 7-hydroxy-Δ1-THC was fast and both substances rapidly penetrated the C.N.S. Peak brain levels of both compounds occurred within 20 min of injection and the correlation between pharmacological response and brain concentration of either compound was equally good. Twenty min after injection more than 50 per cent of the radioactivity in blood was irreversibly bound, whereas only 12 per cent of the activity in brain was unextractable. SKF 525A (25 mg/kg i.p.) produced only a slight increase in the brain level of Δ1-THC but the level of 7-hydroxy-Δ1-THC was increased nearly three-fold, presumably due to the inhibition of subsequent metabolic reactions. Piperonyl butoxide (100 mg/kg i.p.) produced an increase in the brain level of Δ1-THC but no change in the level of 7-hydroxy-Δ1-THC. Higher doses of either inhibitor produced behavioural changes in the absence of Δ1-THC. It is concluded that 7-hydroxy-Δ1-THC is centrally active, but that it has not yet been demonstrated that the effects of injected Δ1-THC are due solely to its primary metabolite.

AbstractAus einem aus Blättern und Blütenköpfen von Cannabis sativa L. (Herkunftsland: Pakistan) gewonnenen Extrakt konnte durch Gegenstromverteilung das n‐Propylhomologe (Ia) ("Δ1‐Tetrahydro‐cannabidivarol") des Δ1‐Tetrahydrocannabinols (Ib) isoliert werden.

The n-propyl homologue of Δ1-tetrahydrocannabinol (Δ1-THC) has been isolated from Cannabis sativa L. The structure of the compound was deduced by i.r., n.m.r., and mass spectroscopy, and was confirmed by synthesis. It has only one-fifth of the activity of Δ1-THC in the mouse catalepsy test, and although present in amounts comparable to Δ1-THC it probably makes only a small contribution to the effects produced by the consumption of crude cannabis.

AbstractDas primäre Hauptprodukt bei der Oxidation von Toluolen wie z.B. (I) durch wäßrige Ammoniumcer(IV)‐nitrat‐LÖsung ist ein Salpetersäureester des Typs (II).

There are at least six pharmacologically effective components of cannabis. Their effects on mice include a lowering of body temperature, catalepsy, analgesia and an extension of barbiturate sleeping time, with doses from 25 to 200 mg/kg.

Reports have appeared that substituted toluenes can be oxidised by ammonium cerium(IV) nitrate in dilute nitric acid solution to the corresponding benzaldehydes in high yield. We find that the major primary reaction product is a benzyl nitrate ester, and that the outcome of the reaction is dependent on the rate of hydrolysis of this nitrate ester, which is followed by rapid oxidation of the substituted benzyl alcohol. Aliphatic hydrocarbon solvents greatly reduce the concentration of nitrate ester in the aqueous phase and prevent hydrolysis. In the absence of solvents toluene is eventually oxidised to benzaldehyde but o-xylene gives 2-methylbenzyl nitrate as the major oxidation product. The nitrate insertion reaction acts in parallel with a hydroxide insertion reaction which yields a substituted benzyl alcohol as an alternative primary reaction product : the small amount of o-tolualdehyde obtained from the oxidation of o-xylene is probably formed from this latter reaction rather than by hydrolysis and further oxidation of the nitrate ester.

Benzilylcholine mustard (N-2-chloroethyl-N-methyl 2-aminoethyl benzilate), a 2-haloalkylamine which cyclizes in solution to form an ethyleniminium derivative structurally very similar to benzilylcholine, was found to be a potent antagonist of the muscarinic action of acetylcholine. It differed from benzilylcholine in showing a much greater persistence of action, which was attributed to the alkylating activity of the ethyleniminium ion. Its action was highly specific, antagonism of the action of histamine and noradrenaline on smooth muscle requiring about 1000 times the concentration needed to block acetylcholine. It did not block ganglionic or neuromuscular transmission, but inhibited parasympathetic effects as well as the muscarinic actions of exogenous acetylcholine. Blocking activity was confined to the ethyleniminium ion: neither the 2-chloroethyl-amine nor the alcoholic hydrolysis product was active. In a study of the rate constants relating to the interaction of benzilylcholine and benzilylcholine mustard with acetylcholine receptors in guinea pig intestinal muscle, it was found that the association rate constant was similar for the two compounds, but that dissociation following alkylation by benzilylcholine mustard occurred at only [unknown] of the rate at which benzilylcholine dissociates. The complex initially formed by benzilylcholine mustard was a reversible one, but alkylation occurred rapidly, the rate of alkylation being considerably greater than that of dissociation of the reversible complex.