Inhibitory Action of Dilazep on Histamine-Stimulated Cytosolic Ca2+ Increase in Cultured Human Endothelial Cells

[摘要] References(32)Cited-By(2)Using a fluorescent Ca2+-sensitive dye, fura-2, and photometric fluorescence microscopy, we measured changes in cytosolic Ca2+ concentration ([Ca2+]i) in cultured human endothelial cells and studied the effect of dilazep on [Ca2+]i elevation induced by histamine. Histamine (1 μM) caused a rapid transient peak in the average [Ca2+]i of a group of cells (approximately 102 cells), followed by a decrease to a sustained elevation. Dilazep as well as diltiazem (1.0 to 100 μM) concentration-dependently inhibited the latter sustained elevation, which was eliminated by removal of extracellular Ca2+, while the initial transient response was not changed by dilazep at concentrations up to 100 μM. The IC50 values of dilazep and diltiazem were 16 and 58 μM, respectively. The patterns of the [Ca2+]i elevation responses to histamine were variable among individual cells. Some single cells showed a transient peak and a sustained elevation as observed in a group of cells. Some single cells caused a repetitive spikelike elevation of [Ca2+]i. Dilazep lowered the sustained elevation to the resting level and in some single cells, changed the sustained elevation to the spikelike elevation. The frequency of the spikelike [Cai]i elevation was also decreased by dilazep. Decrease in extracellular [Ca2+] showed the same pattern of inhibitory actions as dilazep did. These results indicate that dilazep inhibits the extracellular Ca2+ influx in endothelial cells.

[学科分类] 药理学

[关键词] Endothelial cell;Cytosolic Ca2+;Ca2+ spiking;Histamine;Dilazep