Alteration of Ca2+ mobilization and increased circular muscle contractility in colon of stressed rats

目的探讨应激大鼠结肠平滑肌收缩时细胞内外钙离子(Ca2+)利用异常、细胞内钙稳态失衡在导致其收缩性改变中的作用.方法建立寒冷-束缚应激大鼠排便异常的动物模型;测定离体结肠环形平滑肌收缩张力;差速离心制备结肠平滑肌肌浆网,测定肌浆网Ca2+-ATP酶活性.结果应激大鼠结肠平滑肌收缩活性明显增强,并受Ca2+通道阻滞剂显著抑制.应激大鼠结肠平滑肌肌浆网Ca2+-ATP酶活性降低56% (P＜0.05).结论应激大鼠结肠环形平滑肌收缩活性显著增强,可能和肌细胞收缩时细胞外Ca2+内流增加,肌浆网贮存Ca2+释放减少、Ca2+-ATP酶活性降低等因素导致细胞内钙稳态失衡有关.To investigate relationship between the cold-restraint stress induced colonic circular muscle contractility disorder and calcium-handling properties alteration of the affected muscle in rats.Stress was conducted on rats to induce the fecal pellet output increased. Contractile responses to acetylcholine (Ach), KCl, and NaF were determined for colonic circular muscle. To investigate Ca(2+) mobilization, effects of Ca(2+)-free solution, high concentration of extracellular Ca(2+), and pinaverium bromide on the contractility of colon were determined. Prepared sarcoplasmic reticular (SR) of colonic muscle by differential centrifugation and measured Ca(2+)-ATPase activity with colorimetric assay.In stressed rats, contractile responses of colonic circular muscle to Ach, KCl, and NaF increased significantly; the contraction was more sensitive to high concentration of extracellular Ca(2+) than control. In Ca(2+)-free solution, contractions were significantly suppressed in both groups. Pinaverium dose-dependently blocked contractions acting with different sensitivity on the two preparations. The Ca(2+)-ATPase activity of the SR in stress was lower than control.Cold- restraint stress caused a marked increase in the contractility of the colonic circular muscle in rats. Stressed rats' colonic muscle shows an alteration in the homeostasis of intracellular Ca(2+), with appears to be the consequence of increased influx of extracellular Ca(2+), decreased release of intracellular stores of Ca(2+) and a decreased Ca(2+)-ATPase activity of the SR.PubMed中文核心期刊要目总览(PKU)中国科学引文数据库(CSCD)09615-6174