Bumetanide

Loop diuretic that inhibits the Na⁺/2Cl^-/K⁺ (NKCC) cotransporter. More potent than furosemide.

Bumetanide increases Cl--dependent short-circuit current in late distal colon: Evidence for the presence of active electrogenic Cl- absorption.[Pubmed:28152000]

PLoS One. 2017 Feb 2;12(2):e0171045.

Mammalian colonic epithelia consist of cells that are capable of both absorbing and secreting Cl-. The present studies employing Ussing chamber technique identified two opposing short-circuit current (Isc) responses to basolateral Bumetanide in rat distal colon. Apart from the transepithelial Cl--secretory Isc in early distal colon that was inhibited by Bumetanide, Bumetanide also stimulated Isc in late distal colon that had not previously been identified. Since Bumetanide inhibits basolateral Na+-K+-2Cl- cotransporter (NKCC) in crypt cells and basolateral K+-Cl- cotransporter (KCC) in surface epithelium, we proposed this stimulatory Isc could represent a KCC-mediated Cl- absorptive current. In support of this hypothesis, ion substitution experiments established Cl- dependency of this absorptive Isc and transport inhibitor studies demonstrated the involvement of an apical Cl- conductance. Current distribution and RNA sequencing analyses revealed that this Cl- absorptive Isc is closely associated with epithelial Na+ channel (ENaC) but is not dependent on ENaC activity. Thus, inhibition of ENaC by 10 muM amiloride or benzamil neither altered the direction nor its activity. Physiological studies suggested that this Cl- absorptive Isc senses dietary Cl- content; thus when dietary Cl- was low, Cl- absorptive Isc was up-regulated. In contrast, when dietary Cl- was increased, Cl- absorptive Isc was down-regulated. We conclude that an active Cl- extrusion mechanism exists in ENaC-expressing late distal colon and likely operates in parallel with ENaC to facilitate NaCl absorption.

Bumetanide reduce the seizure susceptibility induced by pentylenetetrazol via inhibition of aberrant hippocampal neurogenesis in neonatal rats after hypoxia-ischemia.[Pubmed:28161194]

Brain Res Bull. 2017 Apr;130:188-199.

Hypoxia-ischemia brain damage (HIBD) is one of prevalent causes of neonatal mortality and morbidity. Our data demonstrated that hypoxia-ischemia (HI) induced Na(+)-K(+)-Cl(-)-co-transporter 1 (NKCC1) increasing in hippocampus. Previous studies demonstrated that NKCC1 regulates various stages of neurogenesis. In this study, we studied the role of increased NKCC1 in regulating of HI-induced neurogenesis. HIBD model was established in 7days old Sprague-Dawley rat pup, and the expression of NKCC1 was detected by western blot and qPCR. Brain electrical activity in freely rats was monitored by electroencephalography (EEG) recordings. HI-induced neurogenesis was detected by immunofluorescence staining. Neurobehavioral test was to investigate the neuro-protective role of Bumetanide, an inhibitor of NKCC1, on neonatal rats after HI. The results showed that Bumetanide treatment significantly reduced brain electrical activity and the seizure stage of epilepsy induced by pentylenetetrazol (PTZ) in vivo after HI. In addition, Bumetanide restored aberrant hippocampal neurogenesis and associated cognitive function. Our data demonstrated that Bumetanide reduces the susceptibility of epilepsy induced by PTZ in rats suffering from HI injury during neonatal period via restoring the ectopic newborn neurons in dentate gyrus (DG) and cognitive function.

Effects of bumetanide on neurobehavioral function in children and adolescents with autism spectrum disorders.[Pubmed:28291262]

Transl Psychiatry. 2017 Mar 14;7(3):e1056.

In animal models of autism spectrum disorder (ASD), the NKCC1 chloride-importer inhibitor Bumetanide restores physiological (Cl(-))i levels, enhances GABAergic inhibition and attenuates electrical and behavioral symptoms of ASD. In an earlier phase 2 trial; Bumetanide reduced the severity of ASD in children and adolescents (3-11 years old). Here we report the results of a multicenter phase 2B study primarily to assess dose/response and safety effects of Bumetanide. Efficacy outcome measures included the Childhood Autism Rating Scale (CARS), the Social Responsive Scale (SRS) and the Clinical Global Impressions (CGI) Improvement scale (CGI-I). Eighty-eight patients with ASD spanning across the entire pediatric population (2-18 years old) were subdivided in four age groups and randomized to receive Bumetanide (0.5, 1.0 or 2.0 mg twice daily) or placebo for 3 months. The mean CARS value was significantly improved in the completers group (P: 0.015). Also, 23 treated children had more than a six-point improvement in the CARS compared with only one placebo-treated individual. Bumetanide significantly improved CGI (P: 0.0043) and the SRS score by more than 10 points (P: 0.02). The most frequent adverse events were hypokalemia, increased urine elimination, loss of appetite, dehydration and asthenia. Hypokalemia occurred mainly at the beginning of the treatment at 1.0 and 2.0 mg twice-daily doses and improved gradually with oral potassium supplements. The frequency and incidence of adverse event were directly correlated with the dose of Bumetanide. Therefore, Bumetanide improves the core symptoms of ASD and presents a favorable benefit/risk ratio particularly at 1.0 mg twice daily.

Multiple blood-brain barrier transport mechanisms limit bumetanide accumulation, and therapeutic potential, in the mammalian brain.[Pubmed:28192112]

Neuropharmacology. 2017 May 1;117:182-194.

There is accumulating evidence that Bumetanide, which has been used over decades as a potent loop diuretic, also exerts effects on brain disorders, including autism, neonatal seizures, and epilepsy, which are not related to its effects on the kidney but rather mediated by inhibition of the neuronal Na-K-Cl cotransporter isoform NKCC1. However, following systemic administration, brain levels of Bumetanide are typically below those needed to inhibit NKCC1, which critically limits its clinical use for treating brain disorders. Recently, active efflux transport at the blood-brain barrier (BBB) has been suggested as a process involved in the low brain:plasma ratio of Bumetanide, but it is presently not clear which transporters are involved. Understanding the processes explaining the poor brain penetration of Bumetanide is needed for developing strategies to improve the brain delivery of this drug. In the present study, we administered probenecid and more selective inhibitors of active transport carriers at the BBB directly into the brain of mice to minimize the contribution of peripheral effects on the brain penetration of Bumetanide. Furthermore, in vitro experiments with mouse organic anion transporter 3 (Oat3)-overexpressing Chinese hamster ovary cells were performed to study the interaction of Bumetanide, Bumetanide derivatives, and several known inhibitors of Oats on Oat3-mediated transport. The in vivo experiments demonstrated that the uptake and efflux of Bumetanide at the BBB is much more complex than previously thought. It seems that both restricted passive diffusion and active efflux transport, mediated by Oat3 but also organic anion-transporting polypeptide (Oatp) Oatp1a4 and multidrug resistance protein 4 explain the extremely low brain concentrations that are achieved after systemic administration of Bumetanide, limiting the use of this drug for targeting abnormal expression of neuronal NKCC1 in brain diseases.

Ion and bumetanide binding by the Na-K-Cl cotransporter. Importance of transmembrane domains.[Pubmed:9305921]

J Biol Chem. 1997 Sep 26;272(39):24556-62.

The Na-K-Cl cotransporter (NKCC) plays a key role in electrolyte secretion and absorption across polarized epithelia. The structure of the Na-K-Cl cotransporter transport protein is not known, but from analysis of the primary amino acid sequence and biochemical studies, it has been inferred that the protein has large cytoplasmic N and C termini and a hydrophobic central domain containing 12 transmembrane helices. Both the central domain and the C-terminal domain are highly conserved within the cation-chloride cotransporter family. This paper examines the role of these three domains in interacting with the transported ions and with the inhibitor Bumetanide. We have used a chimera approach, exploiting the functional differences between the structurally similar shark and human secretory Na-K-Cl cotransporters (sNKCC1 and hNKCC1). These transporters are 74% identical to one another and have similar transport and regulatory behaviors; however, sNKCC1 differs markedly from hNKCC1 with regard to apparent affinities for the cotransported ions and for Bumetanide. We prepared six sNKCC1-hNKCC1 chimeras in which N and C termini were interchanged between species. When transfected in HEK-293 cells, each chimera carried out Bumetanide-sensitive 86Rb influx, demonstrating transporter synthesis and cell surface delivery. Monoclonal antibodies J3 and J7 were used to detect the chimeric proteins, and the epitopes for these antibodies were localized to residues 49-196 and 1050-1168, respectively, in the shark sequence. For each of two chimeras that were examined, the time course of activation in low Cl- medium was the same as for the parent proteins; activation was found to proceed through a change in Vmax rather than Km. For the six chimeras, the apparent affinities for Na+, K+, Cl-, and Bumetanide segregated exactly according to whether the large hydrophobic central domain was derived from sNKCC1 or hNKCC1. Significantly, the well-conserved C terminus does not appear to contain residues involved in the shark-human affinity differences. These results demonstrate that residues involved with ion translocation and inhibitor binding are within the large central domain that contains the 12 predicted transmembrane helices.

Characteristics and functions of Na-K-Cl cotransport in epithelial tissues.[Pubmed:3303961]

Am J Physiol. 1987 Aug;253(2 Pt 1):C177-92.

This review summarizes our present understanding of Na-K-Cl cotransport and its physiological role in absorption and secretion of electrolytes and water in epithelial tissues. In the past several years an extensive literature about this cotransporter has developed due to its widespread distribution in a variety of cell types and its essential role in fluid and electrolyte transport in several epithelial tissues. We summarize this literature and speculate on the future characterization of this transport system. Although this review focuses on cotransport as it relates to absorptive and secretory processes in epithelia, important information concerning the pharmacology, stoichiometry, and regulation of Na-K-Cl cotransport in nonepithelial systems (i.e., erythrocytes, fibroblasts, squid axon, etc.) has been included to supplement areas that are less well established in the epithelial literature.

Bumetanide (Ro 10-6338;PF 1593) is a selective Na+-K+-Cl- cotransporter 1 (NKCC1) inhibitor, weakly inhibits NKCC2, with IC50s of 0.68 and 4.0 μM for hNKCC1A and hNKCC2A, respectively.

Bumetanide,28395-03-1,Ro 10-6338; PF 1593,Natural Products,NKCC, buy Bumetanide , Bumetanide supplier , purchase Bumetanide , Bumetanide cost , Bumetanide manufacturer , order Bumetanide , high purity Bumetanide