The urinary excretion of frusemide and its metabolites by kidney transplant patients

Summary Urine from 5 renal transplant recipients treated with frusemide was analyzed for unchanged frusemide (F), glucuronidated frusemide (G) and 4-chloro-5-sulfamoylanthranilic acid (CSA) by HPLC.In 3 recipients, whose renal function recovered steadily and whose hepatic function was normal throughout, the ratio of frusemide to its metabolites, F/(F+G+CSA), increased steadily in conjunction with the recovery of renal function. In one patient, who received frusemide 200–400 mg/day i.v., the urinary CSA concentration was 64–102 µg·ml^–1. In 2 patients who experienced shock and/or hepatic dysfunction after transplantation, the F/(F+G+CSA) ratio fluctuated.     

Roles of dopamine and 5-hydroxytryptamine in stereotyped and non-stereotyped behaviour

The roles of dopamine (DA) and 5-hydroxytryptamine (5-HT) in stereotyped and non-stereotyped components of the classical behavioural syndromes induced by 5-HT and DA were investigated by studying (a) behavioural interactions between the DA agonist apomorphine and the 5-HT agonist 5-methoxy-N,N-dimethyltryptamine (5-MeODMT) and (b) the effects of depletion of 5-HT on the behavioural responses to amphetamine and p-chloroamphetamine. In agreement with evidence [Andrews, Fernando and Curzon (1982) Neuropharmacology 21:63-68] that non-stereotyped (i.e. body shakes and hind limb abduction) and stereotyped (i.e. head weaving and reciprocal forepaw treading) behaviour induced by d-amphetamine (25 mg/kg, i.p.) were inhibited and enhanced respectively by DA, apomorphine inhibited two non-stereotyped behavioural responses induced by 5-MeODMT (hind limb abduction and Straub tail) but enhanced reciprocal forepaw treading. However, head weaving was inhibited. Evidence indicated that behaviour induced by DA (whether stereotyped or not) was inhibited by 5-HT. Thus, the induction by apomorphine of sniffing and mouth movements was enhanced when the synthesis of 5-HT was inhibited. Also, p-chloroamphetamine caused sniffing and mouth movements only when 5-HT synthesis was inhibited. Under the latter conditions, while most classical behavioural responses associated with 5-HT did not occur, hind limb abduction persisted. Similarly, amphetamine (25 mg/kg) caused hind limb abduction and forepaw treading even when 5-HT was almost completely depleted. These results may indicate that the amine releasers have some direct 5-HT agonist properties. Results in general indicate the multiplicity of behavioural interactions between DA and 5-HT.     

Effect of lesioning dopamine,noradrenaline and 5-hydroxytryptamine pathways on tremorine-induced tremor and rigidity

The effects of lesioning monoamine pathways in the rat brain on tremorine-induced hindlimb tremor and rigidity were studied. Nigro-striatal and mesolimbic dopamine (DA) neurones were lesioned unilaterally by injecting 6-hydroxydopamine (6-OHDA) into the median forebrain bundle. Tremor was reduced in the contralateral leg and rigidity was prevented in the ipsilateral leg. Injection of 6-OHDA into the nucleus accumbens affected tremor but not rigidity. In general, nigral DA neurones may influence rigidity whilst mesolimbic DA neurones affect tremor. A unilateral locus coeruleus electrolesion which destroys noradrenaline (NA) fibres reduced both tremor and rigidity. A median raphe electrolytic lesion affecting 5-hydroxytryptamine (5-HT) neurones had no effect on tremor and rigidity. whereas lesioning the dorsal raphe electrolytically or by injecting 5,6-dihydroxytryptamine prevented rigidity without affecting tremor. Electrical stimulation of the dorsal raphe increased transiently the hindlimb tone of normal rats. The findings demonstrate that the monoamines, especially 5-HT, are differently involved in the mechanisms of tremor and rigidity produced by tremorine.     

Cathinone affects dopamine and 5-hydroxytryptamine neurons in vivo as measured by changes in metabolites and synthesis in four forebrain regions in the rat

Cathinone is an active ingredient in the leaves of the Khat shrub. Cathinone affects behavior, neurochemistry and electrophysiology in a manner similar to the stimulants amphetamine, cocaine and methylphenidate. The present study extended these studies by evaluating the effects of (+/-)cathinone on dopamine (DA) and 5-hydroxytryptamine (5-HT)-containing neurons in several regions of the rat brain in vivo. An index of the rate of synthesis of DA and 5-HT in vivo was determined in the nuclei caudatus putamen (CP), accumbens (NA), amygdaloideus centralis (AC), septi lateralis (SL), preopticus pars suprachiasmatica (PSCN) and dorsomedialis (hypothalami; DMN) of male rats (175-225 g) by measuring the concentration of dihydroxyphenylalanine (DOPA) and 5-hydroxytryptophan (5-HTP) after the administration of NSD 1015 (100 mg/kg, i.p.) an inhibitor of aromatic L-amino acid decarboxylase. Concentrations of DA, 5-HT and their major metabolites dihydroxyphenylacetic acid (DOPAC) and 5-hydroxyindoleacetic acid (5-HIAA), respectively, were analyzed by high pressure liquid chromatography coupled to an electrochemical detector. Cathinone decreased levels of DOPAC in a time- and dose-related manner in the caudatus putamen, accumbens, amygdaloideus centralis and septi lateralis with the peak effect occurring 30-60 min after a dose of 6 mg/kg (i.p.). Cathinone had no effect on DOPAC in the preopticus pars suprachiasmatica or dorsomedialis (hypothalami). The drug also decreased the accumulation of DOPA in the caudatus putamen, accumbens, amygdaloideus centralis and septi lateralis, but in the preopticus pars suprachiasmatica and dorsomedialis (hypothalami), there was no effect.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of food on the absorption of frusemide and bumetanide in man

1 The influence of food on the absorption of frusemide and bumetanide was compared in two separate randomized crossover studies. 2 On three separate occasions frusemide 40  mg was administered to eight healthy male volunteers intravenously, orally in the fasting state and orally after a standard breakfast. Blood and urine were collected at intervals over 8  h and urine alone for a further 16  h. The study was then repeated in nine healthy volunteers using intravenous and oral bumetanide 2  mg. 3 Breakfast significantly reduced the peak plasma concentration of frusemide from 2.35±0.49 to 0.51±0.19  mg l⁻¹ (95% confidence intervals (95% CI)=1.39 to 2.28  mg l⁻¹) and delayed the time to peak concentration from 0.69±0.21 to 1.91±0.93  h (95% CI=0.41 to 2.03  h). The oral bioavailability of frusemide was significantly reduced by approximately 30% (75.6±10.6 to 43.2±16.8%; 95% CI=13.5 to 51.4%). 4 With bumetanide, the meal also significantly reduced the peak concentration from 0.097±0.015 to 0.036±0.012  mg l⁻¹ (95% CI=0.048 to 0.073  mg l⁻¹) and delayed the time to peak from 0.53±0.08 to 1.36±0.72  h (95% CI=0.23 to 1.44  h). However, food had no statistically significant effect on the bioavailability and urinary recovery of bumetanide. 5 In this study, the absorption of bumetanide was affected less than frusemide by food.     

Effects of Social Stress on the Turnover of Brain Catecholamines and 5 - Hydroxytryptamine in Mice

Abstract: Male mice were isolated or housed in groups for 10 to 11 weeks. Some of the isolated mice were then brought together in groups of 20. These latter animals began to fight almost immediately. The turnover of brain DA, NA and 5-HT was estimated in such isolated, grouped and fighting animals by measuring the rate of depletion of these monoamines after inhibition of their biosynthesis. The animals were given α-propyl dopacetamide (H 22/54), 500mg/kg intraperitoneally, an inhibitor of tyrosine- and tryptophan-hydroxylase, or the methylester HCl of α-methyl-tyrosine (H 44/68), 250 mg/kg intraperitoneally, an inhibitor of tyrosine-hydroxylase. The H 22/54 induced depletion of NA was similar in the isolated and grouped animals but was accelerated in the fighting animals. The rate of depletion of DA or 5-HT, after H 22/54, did not differ significantly among the isolated, grouped or fighting animals. The H 44/68 induced depletion of NA in the grouped animals was faster than that in isolated animals, while the NA depletion in the fighting animals was faster than that in grouped animals. The H 44/68 induced depletion of DA was more rapid in the fighting than in the isolated animals.     

Blockade of the flare response to intradermal 5-hydroxytryptamine in man by MDL 72.222, a selective antagonist at neuronal 5-hydroxytryptamine receptors

Summary MDL 72.222 is a potent and selective antagonist of excitatory neuronal 5-hydroxytryptamine (5-HT) receptors which has been shown to provide symptomatic benefit in migraine. In the present study, the effects of MDL 72.222 on the flare response to intradermal injection of 5-HT (10^–5, 4×10^–5 and 1.6×10^–4 mol/l) have been examined in six healthy male volunteers using a double-blind, placebo-controlled, randomized, crossover design. The study consisted of two sessions separated by at least 5 days. Comparison of within and between day responses to 5-HT indicated good reproducibility. Significant attenuation of the flare response to 5-HT, 10^–5 and 4×10^–5 mol/l was observed following a slow (4 min) i.v. injection of MDL 72.222, 20 mg. No significant change was observed for the 1.6×10^–4 mol/l dose. The investigator was able to guess with a high degree of accuracy the sequence of MDL 72.222 and placebo (100% correct) and the order of 5-HT dose administration (70% correct), providing further evidence of the reproducibility and sensitivity of the method. MDL 72.222 was well tolerated. Thus, a dose of MDL 72.222 previously shown to provide symptomatic relief in migraine attenuates the flare response to intradermal 5-HT in the human forearm. The observation strengthens the view that the beneficial effects of MDL 72.222 in migraine result from blockade of the sensory neuronal stimulant effects of 5-HT and implies a role for 5-HT in the pain production of the acute attack.     

Reduced platelet phenolsulphotransferase activity towards dopamine and 5-hydroxytryptamine in migraine

Objective: The sulphation of the neurotransmitters dopamine and 5-hydroxytryptamine, and of the prototypical xenobiotic 4-nitrophenol, by phenolsulphotransferases was measured in platelet homogenates prepared from a group of migraine sufferers and a group of control subjects. Results: The activity of the M form of phenolsulpho-transferase, responsible for the sulphation of dopamine and 5-hydroxytryptamine was significantly reduced in the migraine population, by 28% with dopamine as substrate and by 20% with 5-hydroxytryptamine. The activity of the P form of the enzyme towards 4-nitrophenol was the same in both groups. We also report that the selective inhibition of P form phenolsulpho-transferase by red wine is much more potent than previously thought, with a 2000-fold dilution of dealcoholised red wine having the ability to inhibit sulphation by this enzyme by 50%. Conclusion: Our findings suggest that a reduced capacity for sulphation and inactivation of biogenic amines and catecholamines may be related to susceptibility to migraine.Abbreviations 5-HT 5-hydroxytryptamine - ST sulphotransferase - PST phenolsulphotransferase - M-PST monoamine-sulphating form of phenolsulphotransferase - P-PST phenol-sulphating form of phenolsulphotransferase - PAPS 3-phosphadenosine 5-phosphosulphate - IC₅₀ concentration resulting in 50% inhibition of enzyme activity.     

The effect of ageing on the response to frusemide in normal subjects

Summary The effect of IV frusemide was studied in six healthy young (mean age 26.5 years, range 21–33) and six healthy old (mean age 72.8 years, range 66–80) volunteers. A 24-h urine collection before frusemide showed no difference in volume and sodium excretion, although the old excreted less potassium. Creatinine clearance was significantly reduced in the older subjects. After frusemide, 20 mg IV, the pattern of sodium and water excretion over a 5-h period was different in the two groups. The peak effect was greater in the young and occurred within the first 30 min, but was delayed to between 30 and 60 min in the old. Thus in the young the time for 50% of the total sodium and water to be excreted was half that in the old. This delay in sodium and water excretion was related to baseline creatinine clearance. However, the total water, sodium and potassium excreted in the 5 h after frusemide did not differ in the two groups. These results suggest that the renal effects of frusemide are different in healthy elderly subjects as compared to the young. The delayed and reduced peak response is consistent with fewer nephrons in the elderly kidney.     

Interaction of oxindanac and frusemide in man

Summary Oxindanac, a moderately active cyclooxygenase inhibitor in vitro, is a new antinflammatory agent under clinical investigation. Its effects on frusemide-induced natriuresis have now been studied. Eight male volunteers receiving frusemide 40 mg b.d. were also given either oxindanac 300 mg b.d. or placebo in two consecutive periods separated by a treatment-free period, according to a randomized cross-over study design.Urinary prostaglandin excretion (PGF₂) fell by 75% after 3 days on oxindanac. Frusemide-induced renin activity reached 66% of the control value in the presence of oxindanac. However, the natriuresis induced by frusemide did not differ significantly whether oxindanac or placebo was administered, despite the inhibitory action of the former on prostaglandin synthesis in vivo.     

Enhanced 5-hydroxytryptamine and dopamine-mediated behavioural responses following convulsions—I the effects of single and repeated bicuculline-induced seizures

Rats were injected daily with vehicle (controls) or bicuculline (0.375 mg/kg, i.v.) for 10 days. The bicuculline administration produced a major convulsion. Twenty-four hours after the final injection it was found that the bicuculline-treated rats displayed enhanced behavioural responses following the administration of either tranylcypromine (TCP; 5 mg/kg) followed by l-DOPA (50 mg/kg), or of TCP followed by l-tryptophan (75 mg/kg), when responses were compared to controls.The responses following apomorphine or TCP/l-DOPA were also enhanced 24 hr after a single bicuculline injection, whilst those following tranylcypromine/l-tryptophan were unchanged. A single sub-convulsive dose of bicuculline (0.2 mg/kg, i.v.) failed to enhance the TCP/l-DOPA response.When a bicuculline-induced seizure was produced during halothane anaesthesia enhanced TCP/l DOPA responses were not seen 24 hr later, in agreement with the failure of a single electroconvulsive shock (ECS) given during halothane anaesthesia to enhance this response. However an enhanced response was seen 24 hr after a single ECS given without anaesthetic.The possibility that altered monoamine function is a general consequence of repeated convulsions is discussed and the possible role of anaesthetics in retarding these changes is suggested and examined further in the subsequent paper (Cowen, Nutt and Green, Neuropharmacology, 19, 901–906).     

Actions of tetrahydronorharmane (tetrahydro-β-carboline) on 5-hydroxytryptamine and dopamine mediated mechanisms

The activity of 5-hydroxytryptamine (5-HT) or dopamine (DA) containing neurones of rats was blocked either by neurotoxic agents [p-chlorophenylalanine (p-CPA), 6-hydroxydopamine (6-OHDA)], or thermolytic lesions (raphe nuclei, medial forebrain bundle). To assess the effect of the various pretreatments on 5-HT-dependent mechanisms, the hyperactivity-syndrome-test was used. 5-Hydroxytryptophan as well as tetrahydronorharmane (THN) evoked the syndrome in a dose-dependent manner. Combined treatment led to a potentiation of the effects of the single drugs. Lesions of the raphe nuclei reduced the THN-elicited activity syndrome. 6-OHDA had no effect under the same conditions. Injection of 300 mg/kg p-CPA caused a shift to the left of the THN-curve. Following two doses of p-CPA on consecutive days, THN induced a cataleptic syndrome.To assess DA-dependent mechanisms, apomorphine-evoked stereotyped behaviour was used. Pre-treatment with 2 × 300 mg/kg p-CPA as well as lesions of the raphe nuclei reduced the compulsive licking. Thus, the integrity of 5-HT-containing neurones is obviously required for the action of apomorphine.Licking movements were diminished by THN. Pretreatment with 6-OHDA strengthened this action of THN. The effect can be explained by an inhibition of postsynaptic dopaminergic receptors by THN which is not modulated by the stimulating action of 5-HT neurones on DA-containing cells after their destruction by 6-OHDA. The ffect of p-CPA pretreatment and raphe lesions on apomorphine-induced licking was neutralized by THN and this was interpreted as a direct postsynaptic stimulation of 5-HT-receptors.     

Effects of altered brain 5-hydroxytryptaminergic activity on brain tryptophan, 5-hydroxytryptamine and 5-hydroxyindoleacetic acid

The effects of procedures known to alter 5-hydroxytryptaminergic activity (raphe stimulation, raphe lesions and exposure to elevated temperature) on brain tryptophan, 5-hydroxytryptamine and 5-hydroxyindoleacetic acid concentrations were investigated. Electrical stimulation of the dorsal raphe nucleus of unanaesthetised unrestrained rats for 1 hr, using implanted electrodes, significantly increased 5-hydroxyindoleacetic acid concentrations in the hypothalamus, striatum, midbrain and cortex but not in the hippocampus. The level of 5-hydroxytryptamine fell proportionately with the rise of 5-hydroxyindoleacetic acid in the midbrain but did not alter significantly in any other region. Tryptophan concentration was not significantly altered except in the hypothalamus where it increased moderately. Rats kept at 40°C for 60 min had significantly increased plasma and brain tryptophan and brain 5-hydroxyindoleacetic acid. Lysergic acid diethylamide prevented only the increase in 5-hydroxyindoleacetic acid. Electrolytic lesions in the dorsal and median raphe nuclei markedly lowered brain 5-hydroxytryptamine and 5-hydroxyindoleacetic acid but had no effect on brain or plasma tryptophan. Therefore, evidence is against a major role for brain tryptophan changes in the regulation of 5-hydroxytryptamine synthesis following alteration of 5-hydroxytryptaminergic activity. Other possible factors involved in the relationship of 5-hydroxytryptamine metabolism to neuronal activity are discussed.     

Enhanced 5-hydroxytryptamine and dopamine-mediated behavioural responses following convulsions—II the effects of anaesthesia and current conditions on the appearance of enhanced responses following electroconvulsive shock

Rats were given a single electroconvulsive shock (ECS; 125 V 1 sec, 50 Hz) under halothane anaesthesia or were given the anaesthetic only. Twenty-four hours later the behavioural changes which occurred after administration of either tranylcypromine (TCP; 5 mg/kg) followed by l-DOPA (25 mg/kg), or TCP followed by l-tryptophan (50 mg/kg), were similar in both groups. However enhanced responses following TCP/l-DOPA were seen 24 hr after a single ECS, when it was given to unanaesthetised animals. Enhanced responses to TCP/l-DOPA but not to TCP/l-tryptophan were seen 24 hr following ECS given during halothane anaesthesia once daily for 5 days. The anaesthetic did not affect the responses of rats which were not subjected to ECS.When the rats were anaesthetised with methohexitone (5 mg/kg) a similar retardation of the appearance of enhanced behavioural responses was seen. This retardation does not appear to be due to the anaesthetics modifying the severity of the convulsion since administration of either methohexitone or halothane 1 hr after a single ECS to unanaesthetised animals also resulted in the animals not displaying enhanced responses to TCP/l-DOPA.Alteration of the ECS current conditions by increasing the voltage to 200 V (for 1 sec) or prolonging the time of the passage of current (125V for 3 sec) did not result in any greater enhancement of the TCP/l-DOPA responses following ECS once daily for 5 days compared with animals given the “standard rd ECS (125 V, 1 sec).The data demonstrate that the number of ECS required to produce enhanced dopamine-mediated responses (TCP/l-DOPA) were less than those required for enhancement of 5-hydroxytryptaminemediated responses (TCP/l-tryptophan) and that two dissimilar anaesthetics (halothane and methohexitone) retarded the appearance of the enhanced TCP/l-DOPA responses, not by modifying the convulsion but rather by interfering in some way with the mechanisms which occurred following the seizure. Increasing the length of seizure or the voltage passed did not appear to increase the enhancement of the behaviour.     

The effect of nitric oxide inhibition on the renin response to frusemide, in man

AIMS: We wished to see if renin release in man was inhibited by nitric oxide blockade, suggesting a role for nitric oxide in renin release. Evidence from animal studies has shown variable effects on renin release depending on the model and stimulus used. METHODS: Ten normal male volunteers, received either L-NMMA as a front loaded infusion (4 mg kg-1 bolus, with 4 mg kg-1 infusion), or placebo, followed by an intravenous bolus of 5 mg frusemide to stimulate renin. To investigate whether any alteration in renin release was due to the pressor effect of the L-NMMA, the experiment was repeated using an equipressor dose of phenylephrine (0.5 microg kg-1 min-1 ). RESULTS: L-NMMA caused the expected increase in mean arterial pressure (96+/-2.6 vs 89+/-3.3 mmHg P<0.05 [mean+/-s.e.mean]), and a reduction in heart rate (59+/-3.6 vs 67+/-2.5 beats min-1 P<0.05). L-NMMA completely blocked the renin rise following the bolus of frusemide (1.18+/-0.196 vs 1.96+/-0.333 ng ml-1 h-1 P<0.01). Phenylephrine 0.5 microg kg-1 min-1 produced very similar haemodynamic effects to L-NMMA, and also suppressed the renin response to frusemide (1.43+/-0.290 vs 2.67+/-0.342 ng ml-1 h-1 P<0. 01). CONCLUSIONS: In man, the renin inhibition seen with NO synthesis inhibition is similar to that seen with a standard pressor stimulus, hence inhibition of renin in man by L-NMMA, may be due to both direct effects on macula densa cells and indirect haemodynamic effects.     

The action of 5-hydroxytryptamine on single neurones of the rabbit superior cervical ganglion

Intracellular recordings were made from neurones in the rabbit superior cervical ganglion maintained in vitro. Perfusion of the whole ganglion with 5-hydroxytryptamine (5-HT) produced inconsistent and small effects, whereas iontophoretic application of 5-HT induced a depolarization in the majority of neurones. The depolarization was accompanied by a fall in input resistance. The amplitude of the 5-HT potentials was related to the magnitude or duration of the ejection current. The amplitude of the 5-HT potential was augmented by hyperpolarization and decreased by depolarization of the soma membrane of the ganglion cell; it appeared to be linearly related to membrane potential. Iontophoretic responses were reduced in amplitude by superfusion of the ganglion with 5-HT (1 or 50 μM) and by cyproheptadine (50 μM), but unaffected by hexamethonium (500 μM). Tachyphylaxis was apparent when iontophoretic applications were repeated at frequencies of 0.1 Hz or greater.     

A comparison of the locomotor effects of 5-hydroxytryptamine and 5-hydroxytryptophan administered via two systemic routes

This study compared the effects of systemically administered 5-hydroxytryptamine (5-HT) and 5-hydroxytryptamine (5-HT) and 5-hydroxytryptophan (5-HTP) on tilt cage locomotor activity in rats. 5-HT was a more potent inhibitor of activity than 5-HTP via both the s.c. and i.p. routes. The effect of 5-HT itself was greater when administered i.p., whereas the effects of 5-HTP were independent of the route of administration. These results indicate that behavioral changesfollowing 5-HTP injection may be attributable to the peripheral effects of 5-HT.     

γ-l-glutamyl-5-hydroxy-l-tryptophan, but not γ-l-glutamyl-l-tryptophan, causes sodium retention in normal man

1 This randomized, placebo-controlled, cross-over study compared the relative effectiveness of γ-l-glutamyl-5-hydroxy-l-tryptophan (glu-5-HTP) and γ-l-glutamyl-l-tryptophan (glu-TRP) in terms of their ability to act as substrates for renal 5-hydroxytryptamine (5-HT) synthesis and their actions on urinary sodium excretion.
2 Urinary excretion of 5-HT and sodium were determined before, during and after 1  h intravenous infusion of an equimolar amount (45  nmol  kg⁻¹ min⁻¹) of glu-5-HTP or glu-TRP or placebo in nine healthy male subjects.
3 Cumulative urinary 5-HT excretion over the 4  h after the start of glu-5-HTP infusion was 350-fold greater than that after placebo, and this was associated with a reduction in the urinary excretion of sodium.
4 In contrast, the urinary excretion values of 5-HT and sodium after administration of glu-TRP were not significantly different from those observed on the placebo day.
5 The marked increase in urinary 5-HT excretion and the retention of sodium after administration of glu-5-HTP have been demonstrated in previous studies and result from increased intrarenal generation of 5-HT. The absence of a rise in urinary excretion of 5-HT after glu-TRP infusion suggests that there was no significant conversion of this glutamyl compound to 5-HT within the kidney. As a result, there was no effect on urinary sodium excretion.