Characterization of the Endothelin Receptor in Primary Cultures of Human Aortic Smooth Muscle Cells

[摘要] References(29)Cited-By(5)We characterized the endothelin receptor subtypes in primary cultures of human aortic smooth muscle cells (HASMCs) by binding studies. [125I]-Endothelin (ET)-1 saturation experiments showed the existence of a homogeneous population of binding sites with the high affinity (KD value) of 97±37 pM and maximum number of binding sites (Bmax) of 54±10 fmol/mg protein. However, almost no specific [125I]-ET-3 binding was observed. Inhibition of [125I]-ET-1 binding in the HASMCs membrane by nonlabelled compounds showed the following order of effectiveness: ET-1=ET-2=FR139317>ET-3. These results suggest that the endothelin receptor of HASMCs is of the ETA type. We also studied the effect of ET-1 on the cytosolic [Ca2+]i in HASMCs loaded with fura-2/AM. In 1.3 mM Ca2+, ET-1 produced a dose-dependent, biphasic increase in signal with a maximal effect at 10 nM. At this concentration, ET-1 produced a transient increase in [Ca 21]i that reached a peak at 1 min, which was followed by a slow but sustained increase in [Ca2+]i. This second phase was attenuated in Ca2+-deficient medium. Furthermore, ET-1 increased inositol 1, 4, 5-triphosphate in a time and dose-dependent manner. These results suggest that the endothelin receptors of HASMCs are of the ETA type, which couple with Ca2+ channels.

[学科分类] 药理学

[关键词] Endothelin;Receptor;Aorta (human);Smooth muscle cell