Verapamil inhibits serotonin uptake of endothelial cells in culture by a mechanism unrelated to Ca2+ channel blockade

✍ Scribed by S.-L. Lee; K. Long; S. Ueda; B. L. Fanburg

• Book ID: 102883988
• Publisher: John Wiley and Sons
• Year: 1987
• Tongue: English
• Weight: 512 KB
• Volume: 132
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.1041320126

✦ Synopsis

Verapamil inhibited Na+-dependent uptake of serotonin (5-HT) by bovine pulmonary artery endothelial cells in culture both exposed to room air and stimulated by prior exposure to anoxia. The effect of verapamil occurred even in the absence of Ca2+ from the assay medium. Although absence of Ca2+ from the medium moderately reduced 5-HT uptake, stimulation of uptake was nevertheless observed for cells previously exposed to anoxia. Verapamil altered the Km, but not the Vmax, of 5-HT uptake. There was no change in 45Ca2+ uptake or release by cells previously exposed to anoxia as compared to those exposed to room air and verapamil did not influence 45Ca2+ fluxes by either set of cells. It is concluded that verapamil inhibits 5-HT uptake by endothelial cells through a mechanism other than Ca2+ channel blockade; the results are consistent with competitive inhibition of a 5-HT carrier. The stimulatory effect of anoxia on 5-HT uptake does not occur through a change in Ca2+ fluxes.