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The effects of ethanol extracts of Bridelia ferruginea leaves and stem bark on purinergic neurotransmission in the rat bladder were investigated. The stem bark extract potentiated the contraction of the bladder evoked by exogenous adenosine 5-triphosphate (ATP) but depressed KCl-induced contractions in a dose-related pattern; these two opposite actions might account for the lack of effect on field stimulation of the bladder purinergic nerves. The leaf extract depressed purinergic nerve-mediated contraction of the rat bladder in a dose-related fashion. This action could be attributed to blockade of purinergic neurotransmission since the leaf extract did not affect KCl-induced contractions.

The stem bark and leaves of Daniellia oliveri were screened phytochemically and the effects of their respective methanol extracts on the skeletal muscle of rats were investigated using the isolated phrenic nerve hemidiaphragm muscle preparation. Both were found to contain tannins, cardiac and saponin glycosides. In addition, the bark, but not leaves, contained cyanogenetic glycosides. The methanol extracts were found to possess neuromuscular blocking properties. The leaf extract appeared to act primarily by inhibiting the influx of extracellular Ca(2+) principally by inhibiting K(+) channels. The inhibitory action of the bark extract appeared to be mediated by interference with transmitter release and an action on multiple sites., (Copyright 1999 John Wiley & Sons, Ltd.)

The stem bark of Daniellia oliveri was screened phytochemically and a methanol extract prepared.-Condensed tannins, saponins, cyanogenetic and cardiac glycosides were identified in the crude drug. The cardiac glycoside components in the methanol extract were precipitated with acetone to yield a reddish-brown residue. The n-butanol soluble fraction of an aqueous solution of this residue tested positive for cardiac glycosides and was shown by TLC to contain steroidal compounds. This fraction was subjected to pharmacological studies on isolated rat bladder smooth muscle. It had no effect on purinergic neurotransmission but was a noncompetitive antagonist for muscarinic receptors., (Copyright 1999 John-Wiley & Sons, Ltd.)

The pharmacological effects of leaf and seed extracts of Piper guineense were investigated on phrenic nerve hemidiaphragm activity following electrical stimulation in vitro. The Leaf and seed extracts (10 micrograms-1 mg/mL) and (50-800 micrograms/mL) respectively produced biphasic effects consisting of an initial enhancement followed by secondary transient or prolonged depression of twitch tension in response to electrical stimulation of both muscle and nerve. These effects were similar to that of decamethonium (2-800 mg/mL). An increased concentration of extracellular Ca2+ in vitro reversed the twitch contraction inhibited by the leaf and seed extracts in a dose related pattern following electrical stimulation. It is concluded that the leaf and seed extracts of Piper guineense possess among other pharmacological properties, a depolarizing neuromuscular blocking action.

This study examined the influence of overnight storage on endothelium-independent contractions to 5-hydroxytryptamine (5-HT), endothelium-dependent contractions to NG-nitro-L-arginine methyl ester (L-NAME), and endothelium-dependent relaxations to substance P (SP) and L-arginine, using the porcine isolated splenic artery. In endothelium-intact (E+) segments from fresh porcine isolated splenic arteries or segments from the same vessels stored overnight at 4 degrees C, either in Krebs-Henseleit saline or in Krebs-Henseleit saline containing 1 mM L-arginine, 5-HT caused concentration-related contractions that were similar under all three conditions. Overnight storage enhanced contractions of the splenic artery to L-NAME, an effect not observed if the vessels were co-stored with 1 mM L-arginine. L-NAME failed to contract endothelium-denuded (E-) segments from fresh tissues or tissues stored overnight, indicating that its constrictor effects were endothelium-dependent. SP caused concentration-related, endothelium-dependent relaxations of the splenic artery that were inhibited by 100 microM L-NAME, indicating that the relaxations could be attributed to the stimulated release of NO from endothelial cells. Established contractions to 100 microM L-NAME in E+ segments from fresh tissues, or segments from the same tissues stored overnight at 4 degrees C, either in Krebs-Henseleit saline or in Krebs-Henseleit saline containing 1 mM L-arginine, were all reversed by 1 mM L-arginine to similar extents, indicating that overnight storage did not affect endothelium-dependent dilator responses to L-arginine.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects and mechanisms of action of dopamine on the lower oesophagus and expansor secundariorum muscle (ESM) of chicks and on the bladder of rat have been examined. Dopamine contracted the lower oesophagus in a concentration-related fashion but failed to contract the muscle from chicks pretreated with reserpine or p-chlorophenylalanine. Contraction of the ESM by dopamine was antagonized by prazosin but not by propranolol. Supersensitivity of the ESM to dopamine observed 3 or 28 days after surgical denervation of the muscle was comparable. Dopamine did not exert any agonist effect on the rat bladder but depressed responses to stimulation of non-adrenergic, non-cholinergic (NANC) nerves in the bladder. These findings indicate that dopamine contracts the upper oesophagus of chicks by releasing 5-hydroxytryptamine, activates alpha-adrenergic receptors causing contraction of the ESM but depresses NANC neurotransmission in the bladder.

The effects of dopamine on the gastrointestinal tract of chicks have been investigated. Dopamine caused concentration-related contractions of the upper oesophagus, crop or lower oesophagus but relaxed the duodenum, ileum, large intestine or caecum in a concentration-related fashion. By means of specific antagonists, the presence of muscarinic, histamine (H1), alpha-adrenergic, 5-HT-ergic and dopaminergic receptors were established in the lower oesophagus and their stimulation caused contraction while beta-adrenergic-receptor stimulation caused relaxation. Contraction of the lower oesophagus induced by dopamine was abolished by lysergic acid diethylamide and was antagonized by moderate concentrations of haloperidol or pimozide. Tachyphylaxis developed to repeated administration of a large concentration of dopamine. These findings suggest that contraction of the lower oesophagus of chicks by dopamine is largely mediated by 5-hydroxytryptamine release and that stimulation of dopaminergic receptors contributes to a lesser extent.

The functional effects of chronic administration of 60 mg kg-1 chloroquine or quinacrine given as daily intraperitoneal injections for 84 days on normal and denervated expansor secundariorum muscles, a smooth muscle from the wing of chicks wholly innervated by noradrenergic nerves, have been investigated. Administration of quinacrine, but not chloroquine, blocked responses to noradrenergic nerve stimulation. Surgical denervation abolished responses to nerve stimulation. Contraction of the expansor muscle induced by noradrenaline was not changed by chronic administration of chloroquine or quinacrine, and both drugs did not influence denervation supersensitivity of expansor muscles to noradrenaline. Expansor muscles were unresponsive to acetylcholine (ACh) and histamine, but muscles from chicks chronically treated with chloroquine and quinacrine were responsive to ACh and histamine. Denervation also restored the response of expansor muscles to ACh and histamine and the responses were greater for denervated muscles from chronically treated chicks; these changes were more marked with quinacrine. Expansor muscles were contracted by potassium chloride (KCl) and 5-hydroxytryptamine (5-HT), and chronic treatment increased the responsiveness of expansor muscles to KCl. Denervation increased the responsiveness of expansor muscles to KCl and 5-HT; this effect was more pronounced in denervated muscles from quinacrine-treated chicks. The findings indicate that chronic administration of quinacrine sensitizes smooth muscles to agonist drugs by blocking noradrenergic transmission to induce postjunctional changes and exerting a direct action on the smooth muscle; these actions are less pronounced with chloroquine administration.

Sixty patients with chronic granulocytic leukaemia (CGL), anaemia, hyperleucocytosis and hepatosplenomegaly were randomized into 3 treatment schedule consisting of: (i) cyclophosphamide 600 mg/m2 intravenously (i.v.) on day 1. (ii) cytosine arabinoside 100 mg/m2 subcutaneously (sc) 12 hourly for days 1-5. (iii) combination of i.v. cyclophosphamide 600 mg/m2 one day 1 and cytosine arabinoside 100 mg/m2 12 hourly sc for days 1-5. Each cycle of treatment lasted 7 days. Patients on combined chemotherapy achieved laboratory and clinical remission within 28 days of treatment, while patients on single agent chemotherapy of cytosine arabinoside or cyclophosphamide still had hyperleucocytosis and hepatosplenomegaly after 28 days of treatment. Six patients treated with cyclophosphamide only had thrombocytopenic bleeding, but no patient treated with either cytosine arabinoside only or a combination of cytosine arabinoside and cyclophosphamide bled. It is suggested that patients with CGL, anaemia, hyperleucocytosis, and hepatosplenomegaly can be rapidly controlled with a combination of cytosine arabinoside and cyclophosphamide.

The effects of dopamine on non-adrenergic, non-cholinergic (NANC) neurotransmission have been investigated using rat bladder strips in-vitro. Dopamine administered alone did not produce any effect on the bladder but it depressed responses to NANC nerve stimulation in a dose-related fashion. All doses of dopamine employed depressed KCl-evoked contractions of the bladder to similar extents. The depressant action of dopamine on NANC transmission was not mediated by blockade of purinergic receptors, but was partially reversed by haloperidol. It is suggested that depression of NANC neurotransmission induced by dopamine in the rat bladder is partly mediated by dopaminergic receptors.

The possibility that guanidino succinic acid is the major endogenous source of endothelium-derived relaxing factor has been examined using the porcine isolated splenic artery. Administration of 100 microM NG-nitro-L-arginine methyl ester (L-NAME) caused a substantial, endothelium-dependent contraction of the splenic artery that was inhibited by L-arginine (1 mM) but was unaffected by D-arginine (1 mM). L-NAME enhanced the responsiveness of the splenic artery to 5-hydroxytryptamine in endothelium-intact segments only, and the potentiating action of L-NAME was inhibited by L-arginine but not by D-arginine. Administration of 100 microM guanidino succinic acid did not relax the splenic artery and it did not inhibit or reverse contractions of the splenic artery induced by L-NAME. Administration of guanidino succinic acid, either before or after L-NAME, did not affect the potentiating action of L-NAME on the 5-hydroxytryptamine-induced contraction of the splenic artery in endothelium-intact segments. Although substance P caused an endothelium-dependent relaxation of preconstricted segments of the splenic artery, guanidino succinic acid did not relax preconstricted, endothelium-intact or endothelium-denuded segments of the artery. L-NAME inhibited the relaxation induced by substance P in endothelium-intact preparations. The findings for the effects of arginine are consistent with L-arginine being a source of endothelium-derived relaxing factor in the porcine splenic artery, while observations with guanidino succinic acid indicate that it is not a substrate for the synthesis of endothelium-derived relaxing factor in this blood vessel.

The nitric oxide synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME), produced large endothelium-dependent contractions in isolated segments of the porcine splenic artery, equivalent to approximately 30% of the maximum responses to 5-hydroxytryptamine (5-HT). These responses were inhibited by 1mM L-arginine, but not by either 1mM D-arginine or the superoxide anion scavenger, superoxide dismutase. However, L-NAME-induced contractions were markedly inhibited by the cyclooxygenase inhibitor, flurbiprofen, and the lipoxygenase inhibitor, 2,3,5-tri-methyl-6-(12-hydroxy-5,10-dodecadiynyl)1,4-benzoquinone (AA-861). The combined cyclooxygenase and lipoxygenase inhibitor 3-amino-1-[m-(trifluoromethyl)phenyl]-2-pyrazoline (BW-755C) abolished L-NAME-induced contractions. These findings suggest that suppression of endothelial nitric oxide synthase in the porcine isolated splenic artery results in activation of arachidonic metabolism and production of vasoconstrictor eicosanoids.

The functional effects on chick smooth and skeletal muscle of chronic administration of 60 mg kg-1 chloroquine or quinacrine given as daily intraperitoneal injections for 70 days have been investigated. Noradrenaline and potassium chloride (KCl) contracted the normal expansor secundariorum muscle, a smooth muscle from the wing of chicks wholly innervated by noradrenergic nerves. The muscle was unresponsive to acetylcholine and histamine. Chronic administration of chloroquine or quinacrine induced supersensitivity of expansor muscles to KCl and the muscles were contracted by acetylcholine and histamine. These actions were more pronounced in quinacrine-treated chicks and could be due to direct smooth muscle sensitization that may result in postjunctional changes. The oesophagus is a smooth muscle that is predominantly under parasympathetic control. The oesophagus from chronically-treated chicks was more sensitive to acetylcholine and KCl than the control muscles. This sensitization was more marked for chloroquine than quinacrine. Chronic administration of chloroquine and quinacrine depressed skeletal muscle contractions evoked by acetylcholine and potassium chloride. These findings indicate that chronic chloroquine and quinacrine administration sensitise smooth muscle to agonist drugs but depress neuromuscular transmission.

Cyclophosphamide, 40 mg.kg-1, cytosine arabinoside, 2 mg.kg-1 or their combination, were all given once weekly to chicks for 5 weeks. The expansor secundariorum muscle of the left wing of each chick was then surgically denervated leaving that of the right wing to serve as the control. Drug administrations continued for a further 5 weeks before the responses of normal and denervated expansor muscles were determined pharmacologically. Cyclophosphamide depressed the response of the expansor muscle to noradrenergic nerve stimulation but enhanced the response to noradrenaline and potassium chloride. Cytosine arabinoside enhanced responses of expansor muscles to noradrenergic nerve stimulation and noradrenaline, but depressed responses evoked by potassium chloride. The combination enhanced responses to nerve stimulation, noradrenaline, and potassium chloride. Expansor muscles were unresponsive to acetylcholine and anticancer drugs failed to restore the responsiveness to acetylcholine except the combination. Denervation depressed responses to noradrenergic nerve stimulation but caused supersensitivity to noradrenaline; this was more marked in the combination and cyclophosphamide groups, with no change in sensitivity seen in the cytosine arabinoside group. The denervated expansor muscle responded to acetylcholine in the order, combination much greater than cyclophosphamide greater than control greater than cytosine group. Denervated expansor muscles from anticancer groups were supersensitive to potassium chloride, with the combination group having the most pronounced effect. It is suggested that denervation influences smooth muscle sensitivity to agonist drugs which can modify the effects of anticancer drugs on smooth muscle.

The effects of chloroquine diphosphate on body temperature have been investigated in chicks. Chloroquine reduced both central and peripheral temperatures. The hypothermic action of chloroquine depended on the dose administered. The hypothermic action of chloroquine was maximal in chicks less than 6 days post-hatching; this effect decreased with increasing age. It is suggested that the hypothermic effect of chloroquine might contribute to its antipyretic activity in malaria fever.

The receptors in the expansor secundariorum muscle of chicks were characterized pharmacologically and the changes in their response to nerve stimulation and agonist drugs determined during development. The muscle responded to noradrenergic nerve stimulation, noradrenaline and 5-hydroxytryptamine without any change in sensitivity during development. Expansor muscles from 15-day-old chicks were more sensitive to isoprenaline than muscles from older animals. The muscle from 15-day-old chicks responded to acetylcholine and histamine; the sensitivity to both drugs decreased progressively with increasing age of the chicks and disappeared by day 40 posthatching. The normal developmental decrease in response to acetylcholine and histamine were prevented by surgical denervation of the muscle; an intervention that also induced supersensitivity to noradrenaline greater than isoprenaline greater than 5-hydroxytryptamine. The muscle responded to potassium chloride without any change in sensitivity during development or following surgical denervation. These findings indicate that sympathetic nerves influence the responsiveness of the expansor secundariorum muscle to drugs, especially the development decrease in response to acetylcholine and histamine.

The pharmacological effects of repeated administration of 2 mg Kg-1 cytosine arabinoside, 40 mg Kg-1 cyclophosphamide or their combination, all given once weekly for 5 weeks, have been investigated in chicks. Cyclophosphamide did not affect responses to noradrenergic nerve stimulation or phenylephrine, depressed responses of the expansor secundariorum muscle to acetylcholine but sensitised the muscle to direct stimulation. Cytosine arabinoside depressed noradrenergic transmission and enhanced responses of the expansor muscle to phenylephrine and acetylcholine. The combination of both drugs enhanced responses to noradrenergic nerve stimulation due to increased alpha-adrenergic receptor mediated contraction and direct muscle sensitisation. Cyclophosphamide, cytosine arabinoside or their combination produced a non-specific depression of the upper oesophagus and ileum. The exception was the marked increase in response of the ileum from the combination group to agonist drugs, indicating synergism. The non-specific skeletal muscle depressant actions of cyclophosphamide and the combination groups were more pronounced than that of the cytosine arabinoside group.

The in vitro effects of 3 antimalarial compounds (chloroquine, quinacrine and quinidine) on 3 components of the autonomic nervous system have been investigated. The expansor secundariorum muscle was used for studying noradrenergic mechanisms, the chick oesophagus for cholinergic mechanisms, the rat bladder for "purinergic" mechanisms, and the mouse ileum for prostaglandin-mediated responses. Chloroquine reduced responses to noradrenergic and "purinergic" nerve stimulation to similar extents, possibly due to a non-specific effect; it induced supersensitivity to exogenous noradrenaline. Both chloroquine and quinacrine had atropine-like actions in concentrations up to 1 X 10(-4)M; larger concentrations had a direct depressant action on smooth muscle. Quinacrine blocked noradrenergic nerves in a similar fashion to guanethidine but failed to induce supersensitivity to exogenous noradrenaline; it was a potent antagonist of the responses to "purinergic" nerve stimulation. Quinidine blocked responses to "purinergic" nerve stimulation, caused moderate antagonism of alpha-adrenoceptor-mediated effects, but was a weak muscarinic receptor antagonist. The antimalarial compounds were more potent antagonists of prostaglandin-mediated responses than of "purinergic" responses. However, not all their actions could be attributed to prostaglandin antagonism.

The effects of guanethidine, chloroquine and quinacrine on noradrenergic nerves have been compared in vitro using the isolated expansor secundariorum muscle of chicks. The effect of chloroquine on alpha-methyl-noradrenaline uptake by noradrenergic nerve terminals in various tissues were studied. The inhibitory action of guanethidine and quinacrine on noradrenergic nerves appeared to be mediated intraneuronally. The inhibitory action of chloroquine was readily reversible and unaffected by dexamphetamine. Chloroquine caused supersensitivity of the expansor muscle to noradrenaline by blocking its neuronal reuptake since the supersensitivity caused by denervation was not further increased by chloroquine. This was confirmed by the finding that chloroquine inhibited alpha-methylnoradrenaline uptake (Uptake1). Quinacrine did not cause supersensitivity to noradrenaline, possibly due to its direct depressant action on the expansor secundariorum muscle.

1 Changes in the response to acetylcholine of expansor secundariorum muscles from chicks have been analyzed by pharmacological techniques and by [3-3H)-quinuclidinyl benzilate ([3-3H]-QNB) binding to quantify the muscarinic receptor population. 2 The expansor secundariorum muscle responded to acetylcholine up to the age of 30 days; the response declined thereafter. This developmental decrease in response to acetylcholine was prevented by surgical denervation. 3 In chicks aged less than 25 days, denervation did not affect the sensitivity of the expansor muscle to acetylcholine. In order chicks (above 40 days) denervation gradually restored the sensitivity of the expansor muscle to acetylcholine. Responses of the expansor muscle were always abolished by atropine (1 microM) indicating they were mediated by muscarinic receptors. 4 Binding studies with [3-3H]-QNB showed that changes in response of expansor muscle to acetylcholine were primarily due to changes in the muscarinic receptor population. 5 It is suggested that the noradrenergic innervation of the expansor muscle influences the number of muscarinic receptors expressed in the tissue.

The effects of chronic administration of graded doses of chloroquine diphosphate, given by daily intraperitoneal injections for up to 52 days, have been examined using chicks. Some of the factors contributing to the observed effects were investigated. Chloroquine depressed the increase in body weight of growing chicks in a dose-related fashion and reduced the body weight of adult fowl, possibly as a result of reducing food and water intakes. Stunting (as assessed from femur length and circumferential growth) following chronic chloroquine administration was found to be dose-dependent. Chloroquine reduced the dry mass and water content of most muscle types and organs examined especially skeletal muscle, smooth muscle and the spleen. However, there was an increase in the wet and dry mass of the adrenal glands, but only with the lowest dose regimen (30 mg/kg daily for 52 days). Chronic chloroquine treatment reduced the size and the number of smooth muscle cells per bundle in the expansor secundariorum. It also caused bleaching of black feathers and reddening of white feathers.

Nine or 52 day old chicks were treated with daily intraperitoneal of 75 mg/kg chloroquine diphosphate for 14 days. The response of the sympathetically innervated expansor secundariorum muscle to electrical stimulation or to noradrenaline were then measured in vitro. Noradrenergic nerves were examined by fluorescence histochemistry. The main effect observed 30-90 min after the last dose of chloroquine was supersensitivity to exogenous noradrenaline. This was no longer detectable from expansor muscles taken 18-24 h after the last dose of chloroquine. However, noradrenergic nerves in tissues from chronically treated chicks taken 18-24 h after the last dose of chloroquine were less fluorescent than those from control animals. Chronic chloroquine treatment reduced the body weight of chicks. There was also a reduction in the weight of the expansor muscle, due to a reduction in both muscle mass and water content. Surgical denervation increased the weight of the expansor muscle by increasing its muscle mass and abolished the fluorescence of its noradrenergic nerves 3 days after surgery. The denervated expansor muscle responded very weakly to electrical stimulation and its supersensitivity to noradrenaline was maximal 3-5 days after surgery. The denervated expansor muscle developed a lower maximum response to noradrenaline.

The effects of chemical sympathectomy with 6-hydroxydopamine on the response of the expansor secundariorum muscle to noradrenergic nerve stimulation, noradrenaline and acetylcholine have been investigated. Expansor muscles from 60 day old chicks were sensitive to noradrenergic nerve stimulation and exogenous noradrenaline but virtually unresponsive to acetylcholine. Chemical sympathectomy with 6-hydroxydopamine caused loss of function of noradrenergic nerves of the expansor muscle, induced supersensitivity to exogenous noradrenaline and gradually increased the response of the expansor muscle to acetylcholine. As the patency of noradrenergic nerves reappeared there was a decline in the extent of supersensitivity to noradrenaline and the response to acetylcholine gradually declined. The time courses of these changes differed, indicating that the mechanisms responsible for changes in response to noradrenaline and acetycholine are different.