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肌肉收缩和腺体分泌功能,均受细胞质内Ca~(++)的调节。有报道细胞活动时细胞内的Ca~(++)增加100倍。心肌和平滑肌细胞内储存的Ca~(++)有限,收缩活动的维持,有赖于细胞外Ca~(++)源源不断地流入。当细胞受到某些神经体液物质例如去甲肾上腺素的刺激而收缩时,Ca~(++)的流入即开始。Ca~(++)由肌质网和内膜进入并与肌钙蛋白结合,心肌细胞内收缩器即开始起动。细胞内Ca~(++)积聚过多,可引起平滑肌强烈收缩,其典型表现为冠脉痉挛。钙通道阻滞剂,选择性地阻断Ca~(++)经细胞膜的电压依赖性通道(Ca~(++)通道)缓慢内
Muscle contraction and glandular secretion are regulated by intracellular Ca ~ (++). It has been reported that intracellular Ca ~ (++) increases by 100-fold when cells are activated. The storage of Ca ~ (++) in myocardial and smooth muscle cells is limited, and the maintenance of contractile activity depends on the influx of extracellular Ca ~ (++). Influx of Ca ~ (++) begins when cells are contracted by the stimulation of certain neurohumoral substances such as norepinephrine. Ca ~ (++) enters the sarcoplasmic reticulum and endometrium and binds to troponin, and the cardiomyocyte retractor begins to activate. Intracellular Ca ~ (++) accumulation too much, can cause strong contraction of smooth muscle, the typical manifestation of coronary spasm. Calcium channel blockers selectively block Ca ~ (++) via the cell-membrane voltage-dependent channels (Ca ~ (++) channels) slowly