Roles of the plasma membrane in Ca^<2+> oscillations in smooth muscle cells

本研究旨在阐明在豚鼠回肠单个平滑肌细胞受到毒蕈碱受体刺激后，质膜和胞内Ca^<2+>储存在胞内Ca^<2+>浓度振荡中的作用。毒蕈碱受体介导的Ca^<2+>振荡发生不同，因为Ca^<2+>内流与动作电位放电有关，并且Ca^<2+>通过第二信使三磷酸肌醇从内部储存释放。Ca^<2+>储存库衍生的Ca^<2+>振荡需要持续的Ca^<2+>内流来维持和调节振荡频率。Ca^<2+>通道的l型和尚未确定的Ca^<2+>通道可能参与了Ca^<2+>的持续流入。质膜来源的Ca^<2+>振荡类型可能与Ca^<2+>诱导的Ca^<2+>释放没有或很少有关；Ca^<2+>在进入细胞的动作电位放电过程中激活ryanodine敏感，Ca^<2+>门控Ca^<2+>通道在细胞内部储存，从那里释放Ca^<2+>。在Ca^<2+>储存源性Ca^<2+>振荡产生过程中，膜电位与它们同步振荡。细胞膜电位振荡是由毒蕈碱受体操作的非选择性阳离子通道的活性增强引起的，细胞内Ca^<2+>浓度升高。的结果。1、2和3已在国际技术期刊上发表。4项正在提交。

The present study was made to elucidate the role of the plasma membrane and intracelullar Ca^<2+> stores in oscillations in cytosolic Ca^<2+> concentration following stimulation of muscarinic receptors in single smooth muscle cells of guinea-pig ileum.1. The muscarinic receptor-mediated Ca^<2+> oscillations occur differentially because of Ca^<2+> influx across the plasma membrane associated with action potential discharge and of Ca^<2+> release from internal stores by a second messenger, inositol trisphosphate.2. Ca^<2+> store-derived Ca^<2+> oscillations require a sustained Ca^<2+> influx for their persistence and regulation of the oscillation frequency. The L-type of Ca^<2+> channel and an as yet unidentified Ca^<2+> channel may be involved in the sustained Ca^<2+> influx.3. The plasma membrane-derived type of Ca^<2+> oscillation may have no or little contribution from Ca^<2+>-induced Ca^<2+> release ; Ca^<2+> entering the cell during action potential discharge activtes ryanodine-sensitive, Ca^<2+>-gated Ca^<2+> channels in the internal store to release Ca^<2+> from there.4. During generation of Ca^<2+> store-derived Ca^<2+> oscillations, membrane potential oscillates coincidentally in time with them. The membrane potential oscillations result each from potentiation of the activity of muscarinic receptor-operated nonselective cation channels by a rise in cytosolic Ca^<2+> concentration.The results of no.1,2 and 3 have been published in international technical journals and those of no.4 are under submission.