title: HEPES prevents edema in rat brain slices.
abstract: Brain slices gain water when maintained in bicarbonate-buffered artificial cerebro-spinal fluid (ACSF) at 35 degrees C. We previously showed that this edema is linked to glutamate receptor activation and oxidative stress. An additional factor that may contribute to swelling is acidosis, which arises from high CO2 tension in brain slices. To examine the role of acidosis in slice edema, we added N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES) to osmotically balanced ACSF (HEPES-ACSF), thereby increasing buffering capacity beyond that provided by bicarbonate/CO2. Water gain was markedly inhibited in HEPES-ACSF. After 3 h incubation in HEPES-ACSF at 35 degrees C, water gain was limited to that of fresh slices after 1 h recovery in ACSF at room temperature. The effect of HEPES in decreasing slice water gain was concentration dependent from 0.3 to 20 mM. The inhibition of water gain by HEPES suggests that tissue acidosis is a contributing factor in brain slice edema.
authors.affiliation: Department of Physiology, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA.
authors.forename: D G
authors.initials: DG
authors.lastname: MacGregor
authors.forename: M
authors.initials: M
authors.lastname: Chesler
authors.forename: M E
authors.initials: ME
authors.lastname: Rice
mesh_terms: D000138:Acidosis / Q000150:complications* / Q000378:metabolism / Q000503:physiopathology; D000818:Animals; D001834:Body Water / Q000187:drug effects / Q000378:metabolism; D001921:Brain / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D001929:Brain Edema / Q000209:etiology* / Q000503:physiopathology / Q000517:prevention & control*; D002021:Buffers; D004305:Dose-Response Relationship, Drug; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism; D006531:HEPES / Q000494:pharmacology*; D006935:Hypercapnia / Q000150:complications / Q000378:metabolism / Q000503:physiopathology; D008297:Male; D009924:Organ Culture Techniques; D018384:Oxidative Stress / Q000502:physiology; D051381:Rats; D020318:Rats, Long-Evans
chemical_list: D002021:Buffers; D018698:Glutamic Acid; D006531:HEPES