钙拮抗剂TMB-8抑制BHQ,NE和KCl引起的培养乳牛基底动脉单个平滑肌细胞内游离钙的升高

用AR CM MIC阳离子测定系统,测量单个细胞内游离钙浓度(Ca²⁺]i),研究8-(N,N-二乙胺)-n-辛基 3,4,5-三甲氧基苯甲酸酯(TMB-8)对培养乳牛基底动脉平滑肌Ca²⁺]i的作用。在细胞外钙浓度为1.3mmol·L^-1时,TMB-8(30μmol·L^-1)可明显抑制BHQ,NE及KCl引起Ca²⁺]i的升高。在细胞外钙为零+EGTA 0.1mmol·L^-1时,TMB-8(10,30及100μmol·L^-1)可浓度依赖性地降低静息Ca²⁺]i,TMB-8(30μmol·L^-1)可几乎完全阻断BHQ及NE引起Ca²⁺]i的增加。研究表明TMB-8降低培养乳牛基底动脉平滑肌Ca²⁺]i的机制,主要是抑制肌浆网Ca²⁺的释放,或增加肌浆网对Ca²⁺的摄入,并由此间接地抑制细胞外钙的内流。

8-(N,N-DIETHYLAMINO)-n-OCTYL-3,4,5-TRIMETHOXYBENZOATE(TMB-8) REDUCED THE ELEVATION OF [Ca2+]i INDUCED BY BHQ, NE AND KCl IN CULTURED SINGLE SMOOTH MUSCLE CELLS OF THE CALF BASILAR ARTERY

The effect of 8-(N, N-diethylamino)-n-octyl-3,4,5-trimethoxybenzoate (TMB-8) on the elevation of Ca2+]i induced by 2, 5-di (tert-butyl)-1, 4-benzohydroquinone (BHQ), norepinephrine (NE), KCl in cultured single smooth muscle cells of the calf basilar artery was studied by a system of measurement of AR-CM-MIC, using Fura-2/AM as a fluoresent indicator. In the presence of extracellular Ca2+ 1.3 mmol.L-1, the resting Ca2+]i was not changed by TMB-8 (10, 30 and 100 mumol.L-1), but the elevation of Ca2+]i induced by BHQ, NE and KCl were reduced by TMB-8 (30 mumol.L-1) significantly. In Ca2+ free Hank's solution containing EGTA 0.1 mmol.L-1, the resting Ca2+]i was markedly reduced by TMB-8 (10, 30 and 100 mumol.L-1), and the increase of Ca2+]i evoked by BHQ and NE was blocked completely by TMB-8 (30 mumol.L-1). The result suggested that TMB-8 inhibited the Ca2+ release from intracellular stores or increased the up-take of Ca2+ into sarcoplasmic reticulum and the inhibition of Ca(2+)-influx from extracellular site may be an indirect machanism.