Bumetanide Group Research Articles

Combined use of CLP290 and bumetanide alleviates neuropathic pain and its mechanism after spinal cord injury inrats.

We aimed to explore whether the combination of CLP290 and bumetanide maximally improves neuropathic pain following spinal cord injury (SCI) and its possible molecular mechanism. Rats were randomly divided into five groups: Sham, SCI + vehicle, SCI + CLP290, SCI + bumetanide, and SCI + combination (CLP290 + bumetanide). Drug administration commenced on the 7th day post-injury (7 dpi) and continued for 14 days. All rats underwent behavioral assessments for 56 days to comprehensively evaluate the effects of interventions on mechanical pain, thermal pain, cold pain, motor function, and other relevant parameters. Electrophysiological assessments, immunoblotting, and immunofluorescence detection were performed at different timepoints post-injury, with a specific focus on the expression and changes of KCC2 and NKCC1 proteins in the lumbar enlargement of the spinal cord. CLP290 and bumetanide alleviated SCI-associated hypersensitivity and locomotor function, with the combination providing enhanced recovery. The combined treatment group exhibited the most significant improvement in restoring Rate-Dependent Depression (RDD) levels. In the combined treatment group and the two individual drug administration groups, the upregulation of potassium chloride cotransporter 2 (K+-Cl-cotransporter 2, KCC2) expression and downregulation of sodium potassium chloride cotransporter 1 (Na+-K+-Cl-cotransporter 1, NKCC1) expression in the lumbar enlargement area resulted in a significant increase in the KCC2/NKCC1 ratio compared to the SCI + vehicle group, with the most pronounced improvement seen in the combined treatment group. Compared to the SCI + vehicle group, the SCI + bumetanide group showed no significant paw withdrawal thermal latency (PWTL) improvement at 21 and 35 dpi, but a notable enhancement at 56 dpi. In contrast, the SCI + CLP290 group significantly improved PWTL at 21 days, with non-significant changes at 35 and 56 days. At 21 dpi, KCC2 expression was marginally higher in monotherapy groups versus SCI + vehicle, but not significantly. At 56 dpi, only the SCI + bumetanide group showed a significant difference in KCC2 expression compared to the control group. Combined application of CLP290 and bumetanide effectively increases the ratio of KCC2/NKCC1, restores RDD levels, enhancesGABAA receptor-mediated inhibitory function in the spinal cord, and relieves neuropathic pain in SCI; Bumetanide significantly improves neuropathic pain in the long term, whereas CLP290 demonstrates a notable short-term effect.

Effects of bumetanide on neonatal seizures: A systematic review of animal and human studies

BackgroundBumetanide, an inhibitor of the sodium-potassium-chloride cotransporter-1, has been suggested as an adjunct to phenobarbital for treating neonatal seizures. MethodsA systematic review of animal and human studies was conducted to evaluate the efficacy and safety of bumetanide for neonatal seizures. PubMed, Embase, CINAHL and Cochrane databases were searched in March 2023. Results26 animal (rat or mice) studies describing 38 experiments (28 in-vivo and ten in-vitro) and two human studies (one RCT and one open-label dose-finding) were included. The study designs, methods to induce seizures, bumetanide dose, and outcome measures were heterogeneous, with only 4/38 experiments being in animal hypoxia/ischaemia models. Among 38 animal experiments, bumetanide was reported to have antiseizure effects in 21, pro-seizure in six and ineffective in 11. The two human studies (n = 57) did not show the benefits of bumetanide as an add-on agent to phenobarbital in their primary analyses, but one study reported benefit on post-hoc analysis. Overall, hearing impairment was detected in 5/37 surviving infants in the bumetanide group vs. 0/13 in controls. Four of the five infants with hearing impairment had received aminoglycosides concurrently. Other adverse effects reported were diuresis, mild-to-moderate dehydration, hypotension, and electrolyte disturbances. The studies did not report on long-term neurodevelopment. The certainty of the evidence was very low. ConclusionAnimal data suggest that bumetanide has inconsistent effects as an antiseizure medication in neonates. Data from human studies are scarce and raise some concerns regarding ototoxicity when given with aminoglycosides. Well conducted studies in animal models of hypoxic-ischaemic encephalopathy are urgently needed. Future RCTs, if conducted in human neonates, should have an adequate sample size, assess neurodevelopment, minimize using aminoglycosides, be transparent about the potential ototoxicity in the parent information sheet, conduct early hearing tests and have trial-stopping rules that include hearing impairment as an outcome.

Improved symptoms following bumetanide treatment in children aged 3−6 years with autism spectrum disorder: a randomized, double-blind, placebo-controlled trial

With the current limited drug therapy for the core symptoms of autism spectrum disorder (ASD), we herein report a randomized, double-blind, placebo-controlled trial to investigate the efficacy, safety, and potential neural mechanism of bumetanide in children with ASD aged 3−6 years old. A total of 120 children were enrolled into the study and randomly assigned to either 0.5 mg bumetanide or placebo. In the final sample, 119 children received at least one dose of bumetanide (59 children) or placebo (60 children) were included in the final analysis. The primary outcome was a reduction in the Childhood Autism Rating Scale (CARS) score, and the secondary outcomes were the Clinical Global Impressions Scale (CGI) -Global Improvement (CGI-I) score at 3 months and the change from baseline to 3-month in the Autism Diagnostic Observation Schedule (ADOS). Magnetic resonance spectroscopy (MRS) was used to measure γ-aminobutyric acid (GABA) and glutamate neurotransmitter concentrations in the insular cortex (IC) before and after the treatment. As compared with the placebo, bumetanide treatment was significantly better in reducing the severity. No patient withdrew from the trial due to adverse events. The superiority of bumetanide to placebo in reducing insular GABA, measured using MRS, was demonstrated. The clinical improvement was associated with a decrease in insular GABA in the bumetanide group. In conclusion, this trial in a large group of young children with predominantly moderate and severe ASD demonstrated that bumetanide is safe and effective in improving the core symptoms of ASD. However, the clinical significance remains uncertain, and future multi-center clinical trials are required to replicate these findings and confirm the clinical significance using a variety of outcome measures.

Effects of hippocampal Na+-K+-2C1- cotransporter on sevoflurane-induced neurobehavioral impairments in neonatal rats

Objective To discuss the effects of hippocampal Na+-K+ -2C1- cotransporter (NKCC1) on sevoflurane-induced neurobehavioral impairments in neonatal rats. Methods Thirty six 6-day-old male Sprague-Dawley rats were divided into three groups (n=12), according to the random number table method: a control group (group C), a sevoflurane group (group S), and a sevoflurane + bumetanide group (group SB). Group C inhaled 30% oxygen for 6 h, while groups S and SB inhaled 2.1% sevoflurane+30% oxygen for 6 h. Group SB was intraperitoneally injected with bumetanide (1.82 mg/kg) 15 min before sevoflurane inhalation. Then, 4 weeks later, the elevated plus maze and prepulse inhibition (PPI) tests were performed. One week after behavior tests, the hippocampus was harvested. Quantitative real time PCR and Western blot were used to detect the levels of NKCC1 mRNA and protein. Results In the elevated plus maze test, no significant difference was observed in total movement distance among the three groups (P<0.05). Compared with group C, group S spent shortened time of stay in the open arms, presented decreased PPI% corresponding to PP3 and PP6 (P<0.05), and produced increased amounts of hippocampal NKCC1 mRNA and protein (P<0.05). Compared with group S, group SB presented extended time in the open arms, increased PPI% corresponding to PP3 and PP6, and declined amounts of hippocampal NKCC1 mRNA and protein (P<0.05). Conclusions Sevoflurane may cause neurobehavioral damages in neonatal rats, which may be associated with NKCC1. Key words: Sevoflurane; Na+-K+ -2C1- cotransporter; Hippocampus; Neuroethology; Neonatal rats

Symptom improvement in children with autism spectrum disorder following bumetanide administration is associated with decreased GABA/glutamate ratios

Bumetanide has been reported to alter synaptic excitation–inhibition (E-I) balance by potentiating the action of γ-aminobutyric acid (GABA), thereby attenuating the severity of autism spectrum disorder (ASD) in animal models. However, clinical evidence of its efficacy in young patients with ASD is limited. This was investigated in the present clinical trial of 83 patients, randomised to the bumetanide group (bumetanide treatment, 0.5 mg twice daily) or the control group (no bumetanide treatment). Primary [Children Autism Rating Scale (CARS)], secondary [Clinical Global Impressions (CGI)], and exploratory [inhibitory (γ-aminobutyric acid, GABA) and excitatory (glutamate, Glx) neurotransmitter concentrations measured in the insular cortex (IC) and visual cortex (VC) by magnetic resonance spectroscopy (MRS)] outcome measures were evaluated at baseline and at the 3-month follow-up. Side effects were monitored throughout the treatment course. Compared with the control group, the bumetanide group showed significant reduction in symptom severity, as indicated by both total CARS score and number of items assigned a score ≥ 3. The improvement in clinical symptoms was confirmed by CGI. GABA/Glx ratio in both the IC and VC decreased more rapidly over the 3-month period in the bumetanide group than that in the control group. This decrease in the IC was associated with the symptom improvement in the bumetanide group. Our study confirmed the clinical efficacy of bumetanide on alleviating the core symptoms of ASD in young children and it is the first demonstration that the improvement is associated with reduction in GABA/Glx ratios. This study suggests that the GABA/Glx ratio measured by MRS may provide a neuroimaging biomarker for assessing treatment efficacy for bumetanide.

Expression and effect of sodium-potassium-chloride cotransporter on dorsal root ganglion neurons in a rat model of chronic constriction injury.

Sodium-potassium-chloride cotransporter 1 (NKCC1) and potassium-chloride cotransporter 2 (KCC2) are associated with the transmission of peripheral pain. We investigated whether the increase of NKCC1 and KCC2 is associated with peripheral pain transmission in dorsal root ganglion neurons. To this aim, rats with persistent hyperalgesia were randomly divided into four groups. Rats in the control group received no treatment, and the rat sciatic nerve was only exposed in the sham group. Rats in the chronic constriction injury group were established into chronic constriction injury models by ligating sciatic nerve and rats were given bumetanide, an inhibitor of NKCC1, based on chronic constriction injury modeling in the chronic constriction injury + bumetanide group. In the experiment measuring thermal withdrawal latency, bumetanide (15 mg/kg) was intravenously administered. In the patch clamp experiment, bumetanide (10 µg/µL) and acutely isolated dorsal root ganglion neurons (on day 14) were incubated for 1 hour, or bumetanide (5 µg/µL) was intrathecally injected. The Hargreaves test was conducted to detect changes in thermal hyperalgesia in rats. We found that the thermal withdrawal latency of rats was significantly decreased on days 7, 14, and 21 after model establishment. After intravenous injection of bumetanide, the reduction in thermal retraction latency caused by model establishment was significantly inhibited. Immunohistochemistry and western blot assay results revealed that the immune response and protein expression of NKCC1 in dorsal root ganglion neurons of the chronic constriction injury group increased significantly on days 7, 14, and 21 after model establishment. No immune response or protein expression of KCC2 was observed in dorsal root ganglion neurons before and after model establishment. The Cl- (chloride ion) fluorescent probe technique was used to evaluate the change of Cl- concentration in dorsal root ganglion neurons of chronic constriction injury model rats. We found that the relative optical density of N-(ethoxycarbonylmethyl)-6-methoxyquinolinium bromide (a Cl- fluorescent probe whose fluorescence intensity decreases as Cl- concentration increases) in the dorsal root ganglion neurons of the chronic constriction injury group was significantly decreased on days 7 and 14 after model establishment. The whole-cell patch clamp technique revealed that the resting potential and action potential frequency of dorsal root ganglion neurons increased, and the threshold and rheobase of action potentials decreased in the chronic constriction injury group on day 14 after model establishment. After bumetanide administration, the above indicators were significantly suppressed. These results confirm that CCI can induce abnormal overexpression of NKCC1, thereby increasing the Cl- concentration in dorsal root ganglion neurons; this then enhances the excitability of dorsal root ganglion neurons and ultimately promotes hyperalgesia and allodynia. In addition, bumetanide can achieve analgesic effects. All experiments were approved by the Institutional Ethics Review Board at the First Affiliated Hospital, College of Medicine, Shihezi University, China on February 22, 2017 (approval No. A2017-169-01).

Efficiency of combined blocking of aerobic and glycolytic metabolism pathways in treatment of N1-S1 hepatocellular carcinoma in a rat model.

The aim of this study was to determine whether the addition of bumetanide (BU), a glycolytic metabolism pathway inhibitor, to arterial embolization improves tumor necrosis of N1-S1 hepatocellular carcinoma in a rat model. N1-S1 tumors were surgically implanted in the liver of 14 Sprague-Dawley rats. The rats were divided into three groups: In control group (n = 5), 1 ml of normal saline was injected intra-arterially. The tumor in the transarterial embolization group (TAE, n = 4) was embolized using 10 mg of 50-150 μ polyvinyl alcohol (PVA) particles and embolization plus BU group (TAE + BU, n = 5) were embolized with 10 mg of PVA plus 0.04 mg/kg of BU. Tumor volume was measured using two-dimensional ultrasound before intervention and twice a week afterward. Relative tumor volume after the intervention was calculated as the percentage of preinterventional tumor volume. After 4 weeks of observation, the rats were sacrificed for histopathological evaluation. No statistically significant difference was detected in the preintervention tumor sizes between the three groups (P > 0.05). In the control group, the relative tumor volume increased to 142.5% larger than baseline measurements. In the TAE group, the tumor volume decreased by 18.2 ± 12.2%. The tumor volume in the TAE + BU group decrease by 90.4 ± 10.2%, which was 72.2% more than in TAE only group (P < 0.0001). Histopathological evaluation demonstrated no residual tumor in the TAE + BU group. Tumor necrosis significantly increased in N1-S1 tumor that received BU at the time of TAE when compared to TAE alone.

Bumetanide augments the neuroprotective efficacy of phenobarbital plus hypothermia in a neonatal hypoxia–ischemia model

The NaKCl cotransporter NKCC1 facilitates intraneuronal chloride accumulation in the developing brain. Bumetanide (BUM), a clinically available diuretic, inhibits this chloride transporter and augments the antiepileptic effects of phenobarbital (PB) in neonatal rodents. In a neonatal cerebral hypoxia-ischemia (HI) model, elicited by right carotid ligation, followed by 90 min 8% O(2) exposure in 7-d-old (P7) rats, PB increases the neuroprotective efficacy of hypothermia (HT). We evaluated whether BUM influenced the neuroprotective efficacy of combination treatment with PB and HT. P7 rats underwent HI lesioning; 15 min later, all received PB (30 mg/kg), and 10 min later, half received BUM (10 mg/kg, PB-HT+BUM) and half received saline (PB-HT+SAL). One hour after HI, all were cooled (30 °C, 3 h). Contralateral forepaw sensorimotor function and brain damage were evaluated 1-4 wk later. Forepaw functional measures were close to normal in the PB-HT+BUM group, whereas deficits persisted in PB-HT+SAL controls; there were corresponding reductions in right cerebral hemisphere damage (at P35, % damage: PB-HT+BUM, 21 ± 16 vs. 38 ± 20 in controls). These results provide evidence that NKCC1 inhibition amplifies PB bioactivity in the immature brain and suggest that coadministration of PB and BUM may represent a clinically feasible therapy to augment the neuroprotective efficacy of therapeutic HT in asphyxiated neonates.

The Antidepressant-Like Actions of Furosemide, Bumetanide and Nifedipine in the Forced Swim Test in Mice

The effects on down-stream signalling and neuroplasticity are the ways the actions of the presently-used antidepressants, the tricarboxylic acids (TCAs) and the selective serotonin reuptake inhibitors (SSRIs) are enhanced and effected. The present study aims to determine whether the actions of the calcium channel blocker, nifedipine, and the loop diuretics, furosemide and bumetanide are enhanced on chronic administration in the forced swim (FST) model of depression in mice. Six groups (six mice in each group) of male albino mice (25-40g) were used. They were housed in a soundproof laboratory and allowed food and water ad libitum in labeled metal cages. Respective groups were pretreated with 5mg/kg of nifedipine, 10mg/kg of imipramine, 5mg/kg of sertraline, 2.5mg/kg of bumetanide and 10mg/kg of furosemide daily intra-peritoneally for 30 days. A control group received 0.25ml of placebo daily for 30 days. On the test days (Day 1, 15 and 31), the doses were gicen but those on furosemide received 100mg/ kg and the bumetanide group received 75mg/kg intra-peritoneally. Experiment using the forced swim test was then used to evaluate their effect on the prolongation of onset of the period of immobility in mice.The compounds enhanced the prolongation of period of onset of immobility over the acute treatment significantly (F(5,30)= 20.35; (p&lt;0.01) and post-hoc DMR test showed imipramine produced the most significant response with bumetanide producing the least response. The order of magnitude of response was imipramine&gt;sertraline&gt;nifedipine&gt; furosemide&gt;bumetanide.Keywords: FST, imipramine, sertraline, nifedipine, furosemide, bumetanide, chronic.

A Comprehensive Review of the Loop Diuretics: Should Furosemide Be First Line?

To review the literature regarding the pharmacokinetic profiles, comparative safety and efficacy, and comparative costs of loop diuretics to evaluate the current clinical usefulness of furosemide. A search of MEDLINE (1966-June 2009) was conducted using the terms furosemide, torsemide, bumetanide, ethacrynic acid, and loop diuretics. Articles were limited to those written in English. All English-language articles identified from the data sources were reviewed. Studies were eligible if they encompassed pharmacokinetics, comparative safety and efficacy, or comparative costs of the loop diuretics. In patients with heart failure (HF), torsemide demonstrated decreased mortality compared with furosemide in 1 study (2.2% vs 4.5% in the furosemide group; p < 0.05), decreased hospitalizations in 1 study (23 in the torsemide group vs 61 in the furosemide group; p < 0.01), and improved New York Heart Association functional classifications in 2 studies. In the first, 45.8% with torsemide versus 37.2% with furosemide demonstrated improvement in at least one functional class (p = 0.00017). In the second, 40.2% with torsemide and 30.7% with furosemide demonstrated improvement in at least one functional class (p = 0.014). In 2 of 3 studies of patients with cirrhosis, torsemide increased natriuresis and total volume diuresed compared with furosemide in patients with cirrhosis; however, no significant difference between the agents with respect to plasma renin and aldosterone concentrations was demonstrated. In patients with pulmonary hypertension, central venous pressure, capillary wedge pressure, and stroke volume significantly improved from baseline among patients who received torsemide, but not in those who received furosemide, although the intergroup analysis failed to reach statistical significance. Among patients with chronic kidney disease, no significant differences were noted with respect to natriuresis and blood pressure control between the 2 agents; however, in patients with acute kidney injury, patients who received furosemide had a significant improvement in urine output versus the torsemide group. Additionally, 2 trials comparing bumetanide with furosemide were identified, although the results were conflicting. In patients with nephrotic syndrome, bumetanide significantly improved weight loss in the first 4 weeks and in week 20, compared with furosemide. In patients with HF, significant improvement in dyspnea at rest and on exertion was exhibited in the bumetanide group, but not in the furosemide group; no significant difference was noted between the 2 groups when evaluating global assessment. Growing evidence demonstrates more favorable pharmacokinetic profiles of torsemide and bumetanide compared with furosemide. Furthermore, torsemide may be more efficacious and safer than furosemide in patients with HF. A trial comparing all 3 drugs would be required to confirm torsemide as the primary loop diuretic in patients with HF, but based upon limited current evidence, we recommend torsemide over furosemide. Currently, little evidence exists to support either torsemide or bumetanide as first-line treatment over furosemide in patients with other edematous disease states.

Loop Diuretics Increase Bone Turnover and Decrease BMD in Osteopenic Postmenopausal Women: Results From a Randomized Controlled Study With Bumetanide

To study effects of loop diuretics on bone, 87 women were randomized to 1 year of treatment with bumetanide or placebo. Compared with placebo, bumetanide decreased BMD by 2% at the total hip and by 1.4% at the whole body. Levels of biochemical bone markers were lower in the placebo than in the bumetanide group. Thus, treatment with loop diuretics affects bone metabolism. Loop diuretics may affect bone because they increase the renal calcium excretion and alters the diurnal rhythm of plasma PTH levels. We studied the effects of 1 year of treatment with the loop diuretic bumetanide on bone metabolism. In a double-blinded design, 87 healthy postmenopausal women with osteopenia were randomized to 1-year bumetanide treatment 2 mg/day or placebo. BMD, plasma levels of calcitropic hormones, and biochemical bone markers were measured at baseline, after 1 year of treatment (week 52), and 6 months after withdrawal of treatment (week 78). Calcium (800 mg/day) and vitamin D (10 microg/day) were administered to all participants during the entire 1.5-year study period. Compared with placebo, urinary calcium (+17%) and plasma PTH levels (+9%) increased significantly in response to bumetanide. After 1 year of treatment, BMD in the bumetanide compared with the placebo group was significantly decreased by 2% at the total hip and ultradistal forearm and by 1.4% at the whole body. In addition, levels of biochemical markers of bone turnover differed significantly (approximately 20%) between groups, with lower levels in the placebo than in the bumetanide group. Six months after the end of treatment, the effects of bumetanide were weakening. Treatment with loop diuretics affects bone turnover and decreases BMD. Further studies may reveal whether loop diuretics should be considered as a risk factor for fracture.

Bumetanide decreases canine cerebrospinal fluid production. In vivo evidence for NaCl cotransport in the central nervous system.

Na/K/2Cl cotransport carrier plays an important role in fluid absorption and secretion in many epithelial tissues. The role of the carrier, however, in mammalian choroidal cerebrospinal fluid (CSF) production has been controversial. We used ventriculo-cisternal perfusion (VCP) labeled with blue dextran with or without bumetanide and measured choroidal CSF production in anesthetized, and paralyzed, mechanically ventilated dogs. During 3 h of VCP, mean intracerebroventricular and arterial pressures, PaCO2, pH, [HCO3-], and serum osmolality remained normal in both groups (n = 9 in each group). Beginning 90 min after the start of VCP, choroidal CSF production was measured every 15 min. In group I (control group), values for CSF production (means +/- SD) were 49 +/- 20, 49 +/- 21, 51 +/- 21, 51 +/- 23, 48 +/- 20, 56 +/- 24, and 48 +/- 20 microliters/min, at 90, 105, 120, 135, 150, 165, and 180 min, respectively. These values did not differ significantly from each other. In group II (bumetanide group), after baseline control CSF production had been determined at 90 and 105 min, bumetanide (10(-4) mol/liter) was added to VCP. Mean values for CSF production were 54 +/- 15 and 52 +/- 17 microliters/min before, and 39 +/- 25, 34 +/- 19, 28 +/- 10, 30 +/- 17, and 30 +/- 18 microliters/min after addition of bumetanide at 90, 105, 120, 135, 150, 165, and 180 min, respectively. Comparing the two groups, baseline values for CSF production measured at 90 and 105 min did not differ significantly. After addition of bumetanide (group II), however, decrements in CSF production varied from 30 +/- 27% at 120 min to 47 +/- 14% at 150 min, which were significantly different from changes in group I. The results of this study indicate that NaCl cotransport carrier is involved in secretion of CSF in dogs, and inhibition of the transporter results in approximately 50% reduction in CSF production.

Effect of bumetanide in capillary permeability pulmonary oedema.

To determine if bumetanide, like furosemide, improves shunt through pulmonary vasoactivity, 20 dogs with unilobar oleic acid pulmonary oedema were studied. Fractional perfusion and intrapulmonary shunt of the oedematous lobe were measured at: baseline, 1 1/2 hours after oleic acid infusion, 15 minutes later after either 0.1 mg X kg-1 of bumetanide in ten dogs (Bumetanide Group) or without bumetanide in ten dogs (Control Group), and 2 1/2 hours after the oleic acid, the bumetanide being administered immediately after the 1 1/2 hours post-oleic acid measurements. Lobar shunts for the Bumetanide Group were: 9.3 +/- 4.0, 54.3 +/- 13.6, 54.7 +/- 13.6, 38.6 +/- 12.0 per cent and for 8.7 +/- 1.6, 45.1 +/- 8.8, 48.3 +/- 7.8, 70.4 +/- 6.2 per cent. Fractional perfusions of the oedematous lobe were: 29.9 +/- 1, 14.7 +/- 1.1, 14.6 +/- 0.7, 19.3 +/- 1.9 per cent in the Bumetanide Group and 28.6 +/- 2.1, 14.2 +/- 1.1, 14.2 +/- 1.5, and 9.9 +/- 1.1 per cent in CONTROLS. Oedema (wet to body weight ratio) was less (p less than 0.05) in the contralateral lobe (2.5 +/- 0.2 vs. 2.9 +/- 0.3) and the oedematous lobe (4.7 +/- 0.4 vs 6.0 +/- 0.5) after bumetanide-induced diuresis. We conclude that bumetanide decreases shunt by decreasing oedema and not through pulmonary vasoactivity.