Patterns of intracellular and intercellular Ca2+ waves in the longitudinal muscle layer of the murine large intestine in vitro
Patterns of intracellular and intercellular Ca2+ waves in the longitudinal muscle layer of the murine large intestine in vitro
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DOI：
10.1113/jphysiol.2002.018986
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发表时间：
2002-08-15
影响因子：
5.5
通讯作者：
Smith, TK
中科院分区：
文献类型：
--
作者：
Hennig, GW;Smith, CB;Smith, TK
用Fluo-4 AM和ICCD相机在35℃时监测了小鼠盲肠和近端结肠纵层(Lm)的钙波活动。细胞内(在LM细胞内)和细胞间(也在细胞间扩散)都观察到了钙波。细胞内钙波与肌肉缺乏运动有关，而细胞间钙波的强度是细胞内波的五倍，通常与局部收缩有关。在单个LM细胞中同时存在多个细胞内钙波。相邻LM细胞的波不协调，不受TTX(1um)的影响，但可被IP3受体拮抗剂xestospongin-C(Xe-C；2um)或2-氨基乙基二苯基硼酸酯(2-APB；25um)以及ryanodine(10um)阻断。Xe-C阻断后，咖啡因(5 MM)可恢复波活动。NiCl2(1 MM)阻断细胞内钙波，尼卡地平(2um)降低其频率和强度，但不影响其速度，提示肌浆网可能是由细胞外钙内流引起的。细胞间钙波经常以爆发式出现，并迅速传播穿过LM层的相当大的区域，并被庚醇(0.5 mM)阻断。细胞内钙波依赖于神经活动、通过L类钙通道的外部钙离子内流和通过钙诱导的钙释放放大。综上所述，可能降低肌肉兴奋性的细胞内钙波仅限于单个的肌层细胞。它们依赖于体内钙库的钙释放，并可能由细胞外钙内流提供动力。细胞间钙波可能是肌张力、混合和推进的基础，它依赖于神经活动、肌肉动作电位的传播和CICR的放大。
Ca2+ wave activity was monitored in the longitudinal (LM) layer of isolated murine caecum and proximal colon at 35 degreesC with fluo-4 AM and an iCCD camera. Both intracellular (within LM cells) and intercellular (also spreading from cell to cell) Ca2+ waves were observed. Intracellular Ca2+ waves were associated with a lack of muscle movement whereas intercellular Ca2+ waves, which were five times more intense than intracellular waves, were often associated with localized contractions. Several intracellular Ca2+ waves were present at the same time in individual LM cells. Waves in adjacent LM cells were not coordinated and were unaffected by TTX (I muM) but were blocked by IP3 receptor antagonists xestospongin-C (Xe-C; 2 muM) or 2-aminoethyl diphenylborate (2-APB; 25 mum), and by ryanodine (10 muM). Caffeine (5 mm) restored wave activity following blockade with Xe-C. NiCl2 (1 mm) blocked intracellular Ca2+ waves, and nicardipine (2 muM) reduced their frequency and intensity, but did not affect their velocity, suggesting the sarcoplasmic reticulum may be fuelled by extracellular Ca2+ entry. Intercellular Ca2+ waves often occurred in bursts and propagated rapidly across sizeable regions of the LM layer and were blocked by heptanol (0.5 mm). Intercellular Ca2+ waves were dependent upon neural activity, external Ca2+ entry through L-type Ca2+ channels, and amplification via calcium-induced calcium release (CICR). In conclusion, intracellular Ca2+ waves, which may reduce muscle excitability, are confined to individual LM cells. They depend upon Ca2+ release from internal Ca2+ stores and are likely to be fuelled by extracellular Ca2+ entry. Intercellular Ca2+ waves, which are likely to underlie smooth muscle tone, mixing and propulsion, depend upon neural activity, muscle action potential propagation and amplification by CICR.