VESNARINONE INHIBITS ADENOSINE UPTAKE IN ENDOTHELIAL-CELLS, SMOOTH-MUSCLE CELLS AND MYOCYTES, AND MEDIATES CYTOPROTECTION

Vesnarinone is a novel synthetic inotropic agent. Recently, it has bee n reported that vesnarinone inhibits adenosine uptake in the B-lymphoc ytoid cell line. Since extracellular adenosine is cardioprotective, we examined whether vesnarinone inhibits adenosine uptake in cells const ituting the cardiovascular system. 1 mu Ci of [H-3]adenosine was added to cells of the myocyte cell line (C2C12), human coronary smooth musc le cell line (HCASMC), human and bovine coronary endothelial cell line s (HCAEC and BCAEC), bovine arterial endothelial cell line (BAEC), and human umbilical venous endothelial cell line (HUVEC). After 10s - 5 m in, cells were separated from free [H-3]adenosine, and the radioactivi ty was measured. When 0.1-100 mu M of vesnarinone was added to each ce ll line, the uptake of adenosine was inhibited dose-dependently {% inh ibition of [H-3]adenosine uptake at 10 and 30 mu M of vesnarinone: 14 and 33% (C2C12), 47 and 72% (HCASMC), 37 and 58% (HCAEC), 42 and 68% ( BCAEC), 19 and 68% (BAEC), 29 and 59% (HUVEC)). The cellular viability of HCAEC exposed to 60 min of hypoxia and 60min of reoxygenation incr eased from 34 +/- 5 to 67 +/- 6% (Trypan blue exclusion test) and 23 /- 5 to 78 +/- 6% (LDH release), which was completely blunted by 8-sul fophenyltheophylline, an adenosine receptor antagonist, and was partia lly blunted by alpha,beta-methyleneadenosine 5'-diphosphate, an inhibi tor of ecto-5'-nucleotidase. We also found that vesnarinone is cytopro tective against hypoxia and reoxygenation in C2C12 and HCASMC. We conc lude that vesnarinone inhibits the uptake of adenosine in cardiovascul ar cells, which contributes to cytoprotection. (C) 1997 Academic Press Limited.