Maruyama I, Kobayashi M, Yoshida C, Momose K
Department of Pharmacology, School of Pharmaceutical Sciences, Showa University, Tokyo, Japan.
J Pharmacobiodyn. 1987 Aug;10(8):396-403. doi: 10.1248/bpb1978.10.396.
The ultrastructural changes of single smooth muscle cells of guinea pig taenia coli during contraction evoked by Ca2+ (Ca) and carbachol (CCh) were investigated by transmission and scanning electron microscopy. Cells, prepared in the presence of a high concentration (140 mM) of KCl, without addition of Ca, exhibited smooth surfaced contour. The contraction of these cells were dose dependent upon Ca. With the increase in Ca concentration, the contraction was accompanied with formation of processes (0.15 micron thick and 1 micron long), membrane evaginations of various sizes and shapes and cores densely packed with filaments at the bottoms of all evaginations. Cells, prepared in the presence of 0.18 mM Ca and at a physiological concentration (2.7 mM) of KCl, had two populations: One had shallow invaginations of the cell membrane and the other had spinous processes. Cells of both types were responsive to CCh and the spinous processes disappeared during contraction but evagination did not appear. Differences in ultrastructural changes during contractions between single smooth muscle cells and intact tissues may be due to the fact that single cells are mechanically free from adjacent cells and connective tissues. It is also possible that membrane properties change during isolation, particularly when cells are isolated in Ca free medium.
通过透射电子显微镜和扫描电子显微镜研究了豚鼠结肠带单个平滑肌细胞在Ca2+（Ca）和卡巴胆碱（CCh）诱发收缩过程中的超微结构变化。在高浓度（140 mM）KCl存在下制备且未添加Ca的细胞呈现出表面光滑的轮廓。这些细胞的收缩对Ca呈剂量依赖性。随着Ca浓度的增加，收缩伴随着突起的形成（0.15微米厚，1微米长）、各种大小和形状的膜内陷以及所有内陷底部密集排列着细丝的核心。在0.18 mM Ca和生理浓度（2.7 mM）KCl存在下制备的细胞有两种类型：一种细胞膜有浅内陷，另一种有棘状突起。两种类型的细胞对CCh均有反应，收缩过程中棘状突起消失，但未出现内陷。单个平滑肌细胞与完整组织在收缩过程中超微结构变化的差异可能是由于单个细胞在机械上与相邻细胞和结缔组织分离。也有可能在分离过程中膜特性发生变化，特别是当细胞在无Ca培养基中分离时。
