Effect of calcium ionophore A23187 on platelet rolling.

Calcium ionophore A23187 induces platelet rolling favorably in normal and less in tumor microvessels. Superfusion of tumor tissues with calcium ionophore A23187 (20 μM) for 15 minutes causes a 2-fold increase of rolling platelets in LLC-1 (▪) and exerts no effects on BFS-1 () on day 14 after tumor cell implantation. In contrast, treatment of tumor-free preparations resulted in a 3-fold increase of rolling platelets in postcapillary venules of controls (■) on corresponding days compared with tumor groups after chamber preparation. Median ± standard error of the median; n = 6 experimental animals per group, *P < .05 versus controls; ¶P < .05 versus baseline (Kruskal-Wallis and Wilcoxon tests).