Nehls V, Drenckhahn D
Department of Anatomy, Julius-Maximilians-University, Würzburg, Germany.
J Cell Biol. 1991 Apr;113(1):147-54. doi: 10.1083/jcb.113.1.147.
Microvascular pericytes are believed to be involved in various functions such as regulation of capillary blood flow and endothelial proliferation. Since pericytes represent a morphologically heterogeneous cell population ranging from circular smooth musclelike to elongated fibroblast-like morphology it is possible that regulation of blood flow (via contractility) and control of endothelial proliferation (as well as other metabolic functions) may be accomplished by different subsets of pericytes. In the present study we provide evidence for heterogeneity of pericytes at the molecular level by using two novel technical approaches. These are (a) immunostaining of whole mounts of the microvascular beds of the rat mesentery and bovine retina and (b) immunoblotting studies of microdissected retinal microvessels. We show that pericytes of true capillaries (midcapillaries) apparently lack the smooth muscle isoform of alpha-actin whereas transitional pericytes of pre- and postcapillary microvascular segments do express this isoform. Thus, regulation of capillary blood flow may be accomplished by the smooth muscle-related pre- and postcapillary pericytes whereas the nonmuscle pericytes of true capillaries may play a role in other functions.
微血管周细胞被认为参与多种功能，如调节毛细血管血流和内皮细胞增殖。由于周细胞是形态各异的细胞群体，从圆形的平滑肌样到细长的成纤维细胞样形态不等，因此血流调节（通过收缩性）和内皮细胞增殖控制（以及其他代谢功能）可能由不同的周细胞亚群完成。在本研究中，我们通过使用两种新的技术方法，提供了周细胞在分子水平上存在异质性的证据。这两种方法是：（a）对大鼠肠系膜和牛视网膜微血管床的整装标本进行免疫染色，以及（b）对显微解剖的视网膜微血管进行免疫印迹研究。我们发现，真毛细血管（中间毛细血管）的周细胞明显缺乏α-肌动蛋白的平滑肌异构体，而毛细血管前和后微血管段的过渡周细胞则表达这种异构体。因此，毛细血管血流的调节可能由与平滑肌相关的毛细血管前和后周细胞完成，而真毛细血管的非肌肉周细胞可能在其他功能中发挥作用。
