PT  - JOURNAL ARTICLE
AU  - B Goz
AU  - L Jeffs
TI  - The enhancement of the frequency of resistance to N-phosphonoacetyl-L-aspartate and methotrexate by 1-beta-D-arabinofuranosylcytosine: the effect of dipyridamole.
DP  - 1994 Aug 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 480--484
VI  - 270
IP  - 2
4099  - http://jpet.aspetjournals.org/content/270/2/480.short
4100  - http://jpet.aspetjournals.org/content/270/2/480.full
SO  - J Pharmacol Exp Ther1994 Aug 01; 270
AB  - In cultured cells, dipyridamole, in a dose-dependent manner, prevented the enhancement by 1-beta-D-arabinofuranosylcytosine (AraC) of either N-phosphonoacetyl-L-aspartate (PALA)- or methotrexate- resistance frequency. Maximal blockade of enhancement of PALA-resistance frequency occurred if the dipyridamole was added with or within about 20 hr of PALA addition. Thereafter, the effect of dipyridamole decreased. Nitrobenzylthioinosine similarly reduced AraC enhancement of PALA- and methotrexate-resistance frequency. Both dipyridamole and nitrobenzylthioinosine inhibited uridine and thymidine uptake into cells to a similar extent in cells pretreated or not with AraC. Thus, although inhibition of nucleoside uptake would seem a reasonable explanation for the effect on PALA-resistance frequency by dipyridamole, there is no obvious explanation at present of how dipyridamole selectively affects resistance frequency in AraC-pretreated cells.