Actions of 8- (N,N-diethylamino) -n-octyl-3,4,5-trimethoxybenzoate in vascular smooth muscle cell cultures
Chen, Z.; Liu, S.X.; Chiou, G.C.
Zhongguo Yao Li Xue Bao 18(4): 299-303
1997
ISSN/ISBN: 0253-9756 PMID: 10072908 Document Number: 482233
AIM: To study the effects of 8-(N,N-diethylamino)-n-octyl-3, 4, 5-trimethoxybenzoate (TMB-8) on vascular smooth muscle (VSM) cells A7r5. METHODS: The effects of TMB-8 were investigated in A7r5 cell cultures with 45CaCl-2. RESULTS: TMB-8 reduced the intracellular free Ca-2+ concentration, (Ca-2+)-i in a Ca-2+-free medium and blocked Ca-2+ entry from the extracellular site in a regular Ca-2+ medium. The equilibrated total cellular binding of Ca-2+ was in increased by TMB-8 whereas 45Ca-2+ entry activated by both NE and KCl was inhibited. However, the NE-activated Ca-2+ entry was not blocked by TMB-8 if TMB-8 was added together with 45Ca-2+ at a later time instead of by pretreatment. Similar to actions of NE and KCl, depletion of Ca-2+ from sarcoplasmic reticulum (SR) would also activate Ca-2+ entry, which was blocked by TMB-8. When TMB-8 was rinsed out alone or together with NE after pretreatment with NE plus TMB-8 in VSM cells, the inhibitory effect of TMB-8 was not affected. CONCLUSION: TMB-8 not only blocks Ca-2+ entry from the extracellular site, but also enhances Ca-2+ uptake into SR which, indirectly inhibits Ca-2+ entry from the extracellular site.