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The following message was posted to: PharmPK
Dear All
I am doing uptake studies on a cell line using increasing
concentrations of a substrate drug for a particular transporter. I have
used increasing concentration of cold compound whereas the hot
concentration was same in all the used range concentrations. I observed
almost similar DPM (decay per minute) at all the concentrations whereas
when the same values were calculated with respect to the quantity of
total substrate per well (pmol/min/mg of protein), the graph is
following Michaelis-Menton pattern. My questions are
Whether I should proportionally increase the concentration of hot in my
set of concentration range of substrate?
Or Shall I have same concentration of hot and if so then can I have
almost same dpm through out the concentration range?
I will highly appreciate your valuable suggestions.
Best regards
Tom
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The following message was posted to: PharmPK
Tom:
How did you mix your radiolabeled (hot) and your unlabeled (cold)
materials? The dilution principle of a well mixed sample means that as
the concentration (weight/volume) of your sample changes (increases),
the specific activity (cpm/weight) will decrease accordingly. The use
of a radiolabeled compound is as an indicator of your total product,
and for that to be meaningful your cold/hot must be totally mixed at
the beginning of the experiment - that is, before you place your
substance into contact with your cell line.
Professor Walter Wolf, Ph.D. President, Correlative Imaging Council,
Society of Nuclear Medicine
Distinguished Professor of Pharmaceutical Sciences
Director, Pharmacokinetic Imaging Program
Department of Pharmaceutical Sciences, School of Pharmacy
University of Southern California 1985 Zonal Ave., Los Angeles, CA
90089-9121
E-Mail: wwolfw.aaa.usc.edu
Telephone: 323-442-1405
Fax: 323-442-9804
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Copyright 1995-2010 David W. A. Bourne (david@boomer.org)