Sensitive isotope dilution liquid chromatography/tandem mass spectrometry method for quantitative analysis of bumetanide in serum and brain tissue.
ABSTRACT We have developed and validated a simple and sensitive stable isotope dilution liquid chromatography/tandem mass spectrometric (LC-MS/MS) method for the quantification of bumetanide in human serum. Samples were prepared with a simple acetonitrile based protein precipitation. The supernatant was then analyzed directly using LC-MS/MS. Chromatographic separation was achieved on a C18 reversed phase column using a methanol and water gradient. The detection was performed in selected reaction monitoring (SRM) mode via a positive electrospray ionization (ESI) interface. The method had a lower limit of quantification (LLOQ) of 1 ng/mL, linearity up to 1250 ng/mL, intra- and inter-day precision less than 10%, and accuracy within ±10%. This method was also demonstrated to be suitable for the analysis of bumetanide in rat serum and brain tissue. Bumetanide concentrations in rat serum and brain were determined for samples collected at several intervals following intraperitoneal (i.p.) injection of bumetanide, and were used to calculate bumetanide permeability through the blood-brain barrier.
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ABSTRACT: The Na-K-2Cl cotransporter 2 (NKCC2) was thought to be kidney specific. Here we show expression in the brain hypothalamo-neurohypophyseal system (HNS), wherein upregulation follows osmotic stress. The HNS controls osmotic stability through the synthesis and release of the neuropeptide hormone, arginine vasopressin (AVP). AVP travels through the bloodstream to the kidney, where it promotes water conservation. Knockdown of HNS NKCC2 elicited profound effects on fluid balance following ingestion of a high-salt solution-rats produced significantly more urine, concomitant with increases in fluid intake and plasma osmolality. Since NKCC2 is the molecular target of the loop diuretics bumetanide and furosemide, we asked about their effects on HNS function following disturbed water balance. Dehydration-evoked GABA-mediated excitation of AVP neurons was reversed by bumetanide, and furosemide blocked AVP release, both in vivo and in hypothalamic explants. Thus, NKCC2-dependent brain mechanisms that regulate osmotic stability are disrupted by loop diuretics in rats. Copyright © 2015 the authors 0270-6474/15/355144-12$15.00/0.The Journal of Neuroscience : The Official Journal of the Society for Neuroscience 04/2015; 35(13):5144-55. DOI:10.1523/JNEUROSCI.4121-14.2015 · 6.75 Impact Factor
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ABSTRACT: There is a well-described association between infantile epilepsy and pervasive cognitive and behavioral deficits, including a high incidence of autism spectrum disorders. Despite the robustness of the relationship between early-life seizures and the development of autism, the pathophysiological mechanism by which this occurs has not been explored. As a result of increasing evidence that autism is a disorder of brain connectivity we hypothesized that early-life seizures would interrupt normal brain connectivity during brain maturation and result in an autistic phenotype. Normal rat pups underwent recurrent flurothyl-induced seizures from postnatal (P)days 5–14 and then tested, along with controls, for developmental alterations of development brain oscillatory activity from P18–P25. Specifically we wished to understand how normal changes in rhythmicity in and between brain regions change as a function of age and if this rhythmicity is altered or interrupted by early life seizures.Neurobiology of Disease 03/2015; 77. DOI:10.1016/j.nbd.2015.02.015 · 5.20 Impact Factor
Article: Ion Transporters in Brain Tumors[Show abstract] [Hide abstract]
ABSTRACT: Ion transporters are important in regulation of ionic homeostasis, cell volume, and cellular signal transduction under physiological conditions. They have recently emerged as important players in cancer progression. In this review, we discussed two important ion transporter proteins, sodium-potassium-chloride cotransporter isoform 1 (NKCC-1) and sodium-hydrogen exchanger isoform 1 (NHE-1) in Glioblastoma multiforme (GBM) and other malignant tumors. NKCC-1 is a Na+-dependent Cl- transporter that mediates the movement of Na+, K+, and Cl- ions across the plasma membrane and maintains cell volume and intracellular K+ and Cl- homeostasis. NHE-1 is a ubiquitously expressed cell membrane protein which regulates intracellular pH (pHi) and extracellular microdomain (pHe) homeostasis and cell volume. Here, we summarized recent pre-clinical experimental studies on NKCC-1 and NHE-1 in GBM and other malignant tumors, such as breast cancer, hepatocellular carcinoma, and lung cancer cells. These studies illustrated that pharmacological inhibition or down-regulation of these ion transporter proteins reduces proliferation, increases apoptosis, and suppresses migration and invasion of cancer cells. These new findings reveal the potentials of these ion transporters as new targets for cancer diagnosis and/or treatment.Current Medicinal Chemistry 01/2015; 22(999). DOI:10.2174/0929867322666150114151946 · 3.72 Impact Factor