Browsing by Author "Dekanski, D. (33067656600)"

The aim of this study was to determine the mechanism of transport of 3-deazaguanine in the rat heart. We used single-pass, paired-tracer dilution method on isolated and retrogradely perfused rat hearts. The maximal cellular uptake (Umax) and total cellular uptake (Utot) of 3-deazaguanine were determined under control conditions and under influence of possible modifiers. Both Umax and Utot were significantly reduced in the presence of unlabeled 3-deazaguanine (from 19.57±2.02% to 8.14±1.19% and from 16.49±3.65% to 4.70±1.96%, n=6, respectively). The presence of pyrimidine nucleoside thymidine caused the reduction of both Umax and Utot (from 20.03±3.76% to 13.58±3.16% and from 16.43±3.58% to 11.94±3.13%, n=6, respectively). Also, we tested the effect of the absence of sodium ions in perfusion solution (both Umax and Utot significantly reduced from 17.95±2.73% to 16.67±2.16% and from 16.68±2.97% to 14.81±3.04%, n=6, respectively) and the effect of dinitrophenol (both Umax and Utot significantly reduced from 19.09±3.68% to 10.58±3.14% and from 16.86±3.84% to 7.10±3.11%, n=6, respectively). The results of self- and cross-inhibition studies show that the transport of 3-deazaguanine is saturable, energy- and sodium-dependent and that 3-deazaguanine uses endogenous transport systems for thymidine and adenosine for its own transport. © 2006 Akadémiai Kiadó, Budapest.

The purpose of this study was to investigate the characteristics of transport of endogenous nucleosides into cardiac tissue from coronary circulation. The study was performed on the isolated perfused guinea pig heart, using the rapid paired tracers single-pass technique. The maximal cellular uptake (Umax) and total cellular uptake (Utot) of adenosine, deoxyadenosine, thymidine, uridine, and cytidine were determined. The cellular uptake of adenosine was significantly higher than the cellular uptake of other studied nucleosides. To elucidate the mechanisms of nucleoside transport, competition studies were performed and the influence of S-(p-nitrobenzyl)-6-thioinosine (NBTI) and sodium ion absence on Umax and Utot was investigated. Self- and cross-inhibition studies indicated the saturable mechanism of nucleosides transport into cardiac tissue and the involvement of different transport mechanisms for purine and pyrimidine nucleosides. The study also showed that both equilibrative-sensitive (es) and sodium-dependent transport were responsible for adenosine and thymidine cellular uptake. © 2004 NRC Canada.

The purpose of this study was to investigate the characteristics of transport of endogenous nucleosides into cardiac tissue from coronary circulation. The study was performed on the isolated perfused guinea pig heart, using the rapid paired tracers single-pass technique. The maximal cellular uptake (Umax) and total cellular uptake (Utot) of adenosine, deoxyadenosine, thymidine, uridine, and cytidine were determined. The cellular uptake of adenosine was significantly higher than the cellular uptake of other studied nucleosides. To elucidate the mechanisms of nucleoside transport, competition studies were performed and the influence of S-(p-nitrobenzyl)-6-thioinosine (NBTI) and sodium ion absence on Umax and Utot was investigated. Self- and cross-inhibition studies indicated the saturable mechanism of nucleosides transport into cardiac tissue and the involvement of different transport mechanisms for purine and pyrimidine nucleosides. The study also showed that both equilibrative-sensitive (es) and sodium-dependent transport were responsible for adenosine and thymidine cellular uptake. © 2004 NRC Canada.