Voltage- and g-aminobutyric acid-activated membrane currents in the human medulloblastoma cell line MHH-MED-3 Carolina Codina a,1 , Robert Kraft a,1 , Torsten Pietsch b , Marco Prinz c , Christian Steinha È user d , Jorge Cervo  s-Navarro e,f , Stephan Patt a, * a Institute of Pathology (Neuropathology), Friedrich Schiller University Jena, Bachstraûe 18, D-07740 Jena, Germany b Institute of Neuropathology, University of Bonn Medical Center, Sigmund-Freud-Straûe 25, D-53105, Bonn, Germany c Institute of Neuropathology, University Hospital of Zurich, Schmelzbergstraûe 12, CH-8091 Zurich, Switzerland d Experimental Neurobiology, Department of Neurosurgery, University of Bonn Medical Center, Sigmund-Freud-Straûe 25, D-53105 Bonn, Germany e Department of Neuropathology, Free University Berlin, Hindenburgdamm 30, D-12200 Berlin, Germany f Universitat International de Catalunya, c/ Immaculada 22, E-08021 Barcelona, Spain Received 25 February 2000; received in revised form 31 March 2000; accepted 26 April 2000 Abstract The whole-cell patch clamp technique was used to characterize voltage- and neurotransmitter-activated currents in the medulloblastoma cell line MHH-MED-3 and cells from tissue slices and primary cultures of two medulloblastoma biopsies. These preparations revealed similar electrophysiological properties. All tested cells displayed 4-aminopyri- dine-sensitive delayed rectifying K 1 currents, g -aminobutyric acid A receptor-mediated Cl 2 currents and most of them inward recti®er K 1 currents. Transient inward currents were mainly carried by low-voltage activated T-type Ca 21 chan- nels in MHH-MED-3 cells, and tetrodotoxin-sensitive Na 1 channels in cells from the primary culture. From these char- acteristics we conclude that medulloblastoma cells share physiological features with developing cerebellar granule cells at an immature stage. q 2000 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Brain tumors; Human; Medulloblastoma; Patch-clamp; Ion channels; g -Aminobutyric acid receptors Medulloblastomas are embryonal cerebellar tumors formed by primitive neuroepithelial cells [15], which are capable of neuronal differentiation [2] and partially recapi- tulate stages in the maturation of normal neuroblasts [18]. Whereas the electrophysiological features of neuroblasts are well known, those of medulloblastomas are unknown. We addressed the question whether medulloblastoma cells share electrophysiological properties with immature neuronal cells. We used the cell line MHH-MED-3, which exhibits an `early neuronal' phenotype based on the expression of synaptophysin and polysialated `embryonal' N-CAM [13]. MHH-MED-3 cells were cultured in ¯asks using Dulbec- co's modi®ed Eagle's medium (DMEM), supplemented with 10% heat-inactivated human umbilical cord serum [13]. For experiments cells were seeded onto coverslips treated with poly-l-lysine and analyzed 5±20 days after seeding. For comparison, two medulloblastomas obtained from surgery were investigated (named MB1, from a 14- year-old boy, classic medulloblastoma, primary operation; and MB2 from a 17 year-old man, classic medulloblastoma with focal synaptophysin-positivity, 1st recurrence). Several 0.7 mm 3 large pieces of tumor tissue were cut into 150 mm- thick slices using a vibratome (Campden Instruments, Loughborough, UK). Slices were stored at room tempera- ture in a carbogenated (95% O 2 , 5% CO 2 ) solution (arti®cial cerebrospinal ¯uid, aCSF) with the following composition (in mM): NaCl 124, NaHCO 3 24, NaH 2 PO 4 1.2, KCl 5, CaCl 2 1.8, MgCl 2 1.2. For patch-clamp experiments they were placed onto a coverslip and ®xed with a platinum grid with nylon mesh. Cells from a second specimen of tumor MB2 were cultured using DMEM medium containing 10% fetal calf serum. Membrane currents were measured in the whole-cell con®guration of the patch-clamp technique. The recording chamber was continuously perfused (2.5 ml/min) with a standard bath solution containing (in mM): NaCl 150, KCl 5, CaCl 2 2, MgCl 2 1, HEPES 5, pH 7.4. For the measure- ment of Ca 21 channel currents the bath solution contained Neuroscience Letters 287 (2000) 53±56 0304-3940/00/$ - see front matter q 2000 Elsevier Science Ireland Ltd. All rights reserved. PII: S0304-3940(00)01134-4 www.elsevier.com/locate/neulet * Corresponding author. Tel.: 149-3641-933596; fax: 149-3641- 933111. E-mail address: stephan.patt@med.uni-jena.de (S. Patt). 1 Both authors contributed equally to this study.