This application requests renewal of an Independent Scientist Award (ISA) to support Prof James O. Schenk in the Depts of Chemistry and Biochemistry/Biophysics at Washington State University (WSU). The ISA will enhance Prof Schenk's career and professional growth because it will continue to: (a) reduce his administrative and teaching responsibilities, (b) enhance development of experimental approaches to problems in drug abuse, (C) allow maximal efforts using the new models developed during the previously funded period, and (d) provide opportunities for expanding the scope of his research through enhanced and continuing collaborations with others in the field. During the previously funded period Prof Schenk developed a rotating disk voltammetric method to measure time-resolved dopamine (DA) release and reuptake in tissue preparations of striatum, nucleus accumbens, and medial prefrontal cortex as well as in a cell culture system expressing the human dopamine transporter (DAT). The results obtained include proposing multisubstrate mechanisms of DA transport in A9 and A10 DA terminal areas, new insights into the chemistry of DA transport via studies of structure-activity and D2O-solvent isotope effects, an approach to measuring the pre-steady state binding of DA to the actively transporting DAT, evidence that DAT activity may be controlled by presynaptic autoreceptors, development of a kinetic model to distinguish binding of structurally similar and dissimilar DA transport inhibitors, and mechanistic insights on changes in the function of DAT following withdrawal from contingent and non-contingent treatments with cocaine. In addition, the technique has been shared with other interested research groups including the laboratories of Prof B. Sorg (WSU), Prof P. Kalivas (WSU), Prof. J. Justice (Emory University), Prof. Diane Latteman (University of WA, Seattle), Prof. R. N. Adams (Univ. of KS) and the labs of Profs. K. Neve, A. Janowsky, and A. Eshleman at the VA Medical Center at the Oregon Health Sciences Univ. (Portland, OR). Work proposed for the next period of research includes, correlations of DA transport at DAT with intracellular changes in ion cosubstrate (Na+ and Cl-) concentrations, continued in vivo and in vitro studies of DA transport mechanisms and actions of inhibitors in DA terminal regions of the rat, studies of human DAT mechanisms and actions of inhibitors in expression systems (such as in HEK-293 cells and N2A cells), studies of bi-directional transport of substrates by DAT, and studies of the action of second messengers on DAT functioning.

National Institute of Health (NIH)
National Institute on Drug Abuse (NIDA)
Research Scientist Development Award - Research (K02)
Project #
Application #
Study Section
Special Emphasis Panel (ZDA1-MXS-M (09))
Program Officer
Pilotte, Nancy S
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Washington State University
Schools of Arts and Sciences
United States
Zip Code
Robinson, Donita L; Volz, Trent J; Schenk, James O et al. (2005) Acute ethanol decreases dopamine transporter velocity in rat striatum: in vivo and in vitro electrochemical measurements. Alcohol Clin Exp Res 29:746-55
Schenk, James O; Wright, Cortney; Bjorklund, Nicole (2005) Unraveling neuronal dopamine transporter mechanisms with rotating disk electrode voltammetry. J Neurosci Methods 143:41-7
Volz, Trent J; Schenk, James O (2005) A comprehensive atlas of the topography of functional groups of the dopamine transporter. Synapse 58:72-94
Volz, Trent J; Bjorklund, Nicole L; Schenk, James O (2005) Methylphenidate analogs with behavioral differences interact differently with arginine residues on the dopamine transporter in rat striatum. Synapse 57:175-8
Volz, Trent J; Schenk, James O (2004) L-arginine increases dopamine transporter activity in rat striatum via a nitric oxide synthase-dependent mechanism. Synapse 54:173-82
Volz, Trent J; Kim, M; Schenk, James O (2004) Covalent and noncovalent chemical modifications of arginine residues decrease dopamine transporter activity. Synapse 52:272-82
Schenk, James O; George, Shannon E; Schumacher, Paul Dietrich (2003) What can be learned from studies of multisubstrate mechanisms of neuronal dopamine transport? Eur J Pharmacol 479:223-8
Wayment, H K; Schenk, J O; Sorg, B A (2001) Characterization of extracellular dopamine clearance in the medial prefrontal cortex: role of monoamine uptake and monoamine oxidase inhibition. J Neurosci 21:35-44
Earles, C; Schenk, J O (1999) Multisubtrate mechanism for the inward transport of dopamine by the human dopamine transporter expressed in HEK cells and its inhibition by cocaine. Synapse 33:230-8
Wayment, H K; Deutsch, H; Schweri, M M et al. (1999) Effects of methylphenidate analogues on phenethylamine substrates for the striatal dopamine transporter: potential as amphetamine antagonists? J Neurochem 72:1266-74

Showing the most recent 10 out of 20 publications