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Cyclosporine uptake by cultured human proximal tubule cells
Author(s) -
Kahng Myong Won,
Lee Jung Young,
Trifillis Anna L.
Publication year - 1991
Publication title -
drug development research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.582
H-Index - 60
eISSN - 1098-2299
pISSN - 0272-4391
DOI - 10.1002/ddr.430240113
Subject(s) - digitonin , verapamil , cytosol , chemistry , incubation , calcium channel blocker , vinblastine , biochemistry , calcium , microbiology and biotechnology , biophysics , pharmacology , endocrinology , medicine , biology , enzyme , organic chemistry , chemotherapy
Characteristics of cyclosporine A (CsA) uptake in cultured normal human proximal tubule cells (PTC) have been studied. The uptake was very rapid, concentration dependent, and reached a steady state level within 10 min. Kinetic analysis yielded an apparent Km of 5.0 μM and V max of 66.7 pmoles/min μg DNA. Verapamil, a calcium channel blocker, at 0.1, 0.5, and 1.0 mM had no inhibitory effect on CsA uptake. Subcellular distribution of CsA following 1, 2, 5, and 10 min incubation of PTC suspension was determined by digitonin differential solubilization. The cytosol fraction contained 26% and the nuclear fraction contained 74% of CsA at all time periods studied. These studies demonstrate that in normal human renal PTC, uptake of CsA is rapid and saturable. Most of the CsA, once taken up by the human PTC, is concentrated in the nucleus.