Phone: (412) 624-4295

Fax: (412) 624-4393
Email: jjohnson@pitt.edu

Ph.D., Stanford University

Research Interests

Ion channels are fundamental to the movement and processing of information in all nervous systems, and therefore are attractive research subjects for neuroscientists. Ion channels are a fascinating research topic for additional reasons: they are remarkably well-designed multifunctional machines that are both challenging and great fun to study. Professor Johnson's laboratory uses biophysical, electrophysiological, molecular, optical, and pharmacological approaches to study the function, structure, and regulation of ion channels. We focus on channels involved in synaptic communication within the vertebrate nervous system.

Of particular interest to the laboratory are N-methyl-D-aspartate (NMDA) receptors, ligand-gated ion channels that are members of the glutamate receptor family. Glutamate receptors mediate most of the fast excitatory synaptic transmission in vertebrate nervous systems. NMDA receptors are unusual receptors in many respects. Some of their unusual characteristics permit them to play pivotal roles in, for example, brain development, and learning and memory. NMDA receptors are also involved in many nervous system disorders, including epilepsy, schizophrenia, ischemia, and a variety of neurodegenerative diseases. We examine the mechanisms that underlie channel permeation, block, gating, and regulation, predominantly of NMDA receptors, but also of other types of glutamate receptors and of inhibitory glycine receptors. The techniques we use include whole-cell and single-channel patch clamp recording from brain slices, cultured neurons, and transfected cell lines, site-directed mutagenesis, and optical imaging of changes in Ca2+ concentration. The insight we gain into receptor properties and structure will lead to an improved understanding receptor involvement in both normal function and dysfunction of the nervous system.

Recent Publications

• Blanpied TA, Clarke RJ, Johnson JW: Amantadine inhibits NMDA receptors by accelerating channel closure during channel block. J Neurosci 25: 3312-3322, 2005.
• Qian A, Buller AL, Johnson JW: NR2 subunit dependence of NMDA receptor channel block by external Mg2+. J Physiol 562: 319-331, 2005.
• Johnson JW: Acid tests of N-methyl-d-aspartate receptor gating basics. Molec Pharmacol 63: 1199-1201, 2003.
• Qian A, Antonov SM, Johnson JW: Modulation by permeant ions of Mg2+ inhibition of NMDA-activated whole-cell currents in rat cortical neurons. J Physiol 538: 65-7, 2002.
• Li-Smerin Y, Levitan ES, Johnson JW: Free intracellular Mg2+ concentration and inhibition of NMDA responses in cultured rat neurons. J Physiol 533: 729-743, 2001.
• Antonov SM, Gmiro VE, Johnson JW: Binding sites for permeant ions in the channel of NMDA receptors and their effects on channel block. Nature Neurosci 1: 451-461, 1998.