[钙离子与冠状动脉痉挛]血管平滑肌的收缩和张力,取决于肌细胞内对收缩蛋白有效的游离钙离子的增加。细胞内的钙离子大部份来源于细胞外,但也有些来源于细胞内,可能是由肌质网、浆膜表面小泡或线粒体所释放。α—肾上腺能兴奋,通过以上两种来源的钙使细胞内的钙离子增加,从而引起血管平滑肌细胞收缩。 [Calcium and Coronary Artery Spasm] The contraction and tension of vascular smooth muscle depends on the increase of free calcium ions effective in contracting protein in muscle cells. Most of the intracellular calcium ions from the extracellular, but also some come from the cells, may be the sarcoplasmic reticulum, serosal surface vesicles or mitochondria release. Alpha-adrenergic can be excited by the above two sources of calcium to increase intracellular calcium, causing vascular smooth muscle cell contraction.