Der Feinere Bau der Blutcapillaren

Zimmermann, K. W.

doi:10.1007/978-3-642-92456-9

Cited by 179 publications

(149 citation statements)

References 34 publications

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“…By light microscopy, diffuse DAB reaction product was visible in pericytes and the staining patterns were very similar to those previously described (17). Because pericytes, especially those on capillaries, are highly elongated cells (17,24,37), the staining pattern obtained depended on where along its length the cell was sectioned. For example, when a pericyte was sectioned through the cell body, as in Fig.…”

Section: Immunoperoxidase Localization Of Tropomyosin In Capillary Ansupporting

confidence: 83%

“…In fact, gradual shape changes have been observed in the transition from vascular smooth muscle cells to pericytes at both the arteriolar and venular end of the microvascular bed (17,19,37), suggesting that there is no clear demarcation between these cell types within the microvasculature. In all the organs examined, the vascular smooth muscle cells of arterioles and muscular venules were well penetrated by antibody and highly reactive for tropomyosin.…”

Section: Discussionmentioning

confidence: 99%

“…In addition, the foot processes have densities that appear similar to the attachment plaques and dense bodies of smooth muscle cells (29,32,34). The presence of such structures within circumferentially oriented pericyte processes suggests a poten-tial contractile function that may contribute to the regulation of blood flow in the microvasculature (12,19,24,37).…”

mentioning

confidence: 99%

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Contractile proteins in pericytes. I. Immunoperoxidase localization of tropomyosin.

Joyce¹,

Haire²,

Palade³

1985

The Journal of Cell Biology

147

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In these studies we have compared the relative amounts and isoforms of tropomyosin in capillary and postcapillary venule pericytes, endothelial cells, and vascular smooth muscle cells in four rat microvascular beds: heart, diaphragm, pancreas, and the intestinal mucosa. The results, obtained by in situ immunoperoxidase localization, indicate that (a) tropomyosin is present in capillary and postcapillary venule pericytes in relatively high concentration; (b) the tropomyosin content of pericytes appears to be somewhat lower than in vascular smooth muscle cells but higher than in endothelia and other vessel-associated cells; and (c) pericytes, unlike endothelia and other nonmuscle cells, contain detectable levels of tropomyosin immunologically related to the smooth muscle isoform. These results and our previous findings concerning the presence of a cyclic GMP-dependent protein kinase (Joyce, N., P. DeCamilli, and J. Boyles, 1984, Microvasc. Res. 28:206-219) in pericytes demonstrate that these cells contain significant amounts of at least two proteins important for contraction regulation. Taken together, the evidence suggests that pericytes are contractile elements related to vascular smooth muscle cells, possibly involved, as are the latter, in the regulation of blood flow through the microvasculature.Pericytes are polymorphic cells closely associated with the walls of capillaries and postcapillary venules. They have a cell body which is often highly elongated, and multiple branching foot processes which partially encircle the vessel wall. Pericytes can be distinguished from other perivascular cells, such as adventitial fibroblasts, by their location within the basement membrane of the vessels, and by the close apposition of the tips of their processes to the underlying endothelium. Electron microscopic studies have identified pericytes in a number of tissues and organs (I0, 12, 20, 36). They may, in fact, be common to all microvascular beds, although their relative frequency and distribution appear to vary from one microvascular bed to another (32,33).The function of pericytes is still unclear; however, morphologic evidence suggests that they may be contractile cells related to vascular smooth muscle. Numerous micro filaments form a continuous plate in the adluminal cytoplasm of their cell body and extend from it into the foot processes, where, in the more distal segments, they fill the cytoplasm to the relative exclusion of other subeellular components. In addition, the foot processes have densities that appear similar to the attachment plaques and dense bodies of smooth muscle cells (29,32,34). The presence of such structures within circumferentially oriented pericyte processes suggests a poten-

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Section: Immunoperoxidase Localization Of Tropomyosin In Capillary Ansupporting

confidence: 83%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Contractile proteins in pericytes. I. Immunoperoxidase localization of tropomyosin.

Joyce¹,

Haire²,

Palade³

1985

The Journal of Cell Biology

147

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“…Fujiwara et al 22 found from scanning electron microscopic observation that pericytes exist in the vascular wall and feature many cytoplasmic processes with octopus-or star-shaped extensions. Zimmermann 23 hypothesized that pericytes with cytoplasmic extensions vertical to the long axis of the capillary vessel may contribute to vasoconstriction. The validity of this assumption can be con®rmed from ®ndings as follows: First, a cell designated as`t ransitional' with a morphology characteristic of both smooth muscle cell and pericyte has been observed at the distal site of the arteriole 24 and, second, certain proteins contributing to vasoconstriction in the smooth muscle are also found in pericytes as immunohistochemical evidence.…”

Section: Discussionmentioning

confidence: 99%

Regulation of vasomotion of arterioles and capillaries in the cat spinal cord: role of α actin and endothelin-1

et al. 1997

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Ring-shaped vasoconstrictions of arterioles at their branching sites have often been reported in vascular corrosion casts of the brain and spinal cord in rats and cats. It is surmised that smooth muscle cells in arteriolar walls could regulate the blood¯ow by changing the diameter of the lumen (ie vasomotion). However, few reports have described vasomotion at the capillary (capillaries have no smooth muscle cells). Also, there have been no reports on endothelin-1 in the arterioles and capillaries of the spinal cord. This study was designed to determine (1) the electron microscopic architecture of vasomotion; (2) the immunohistochemical identi®cation of a actin and endothelin-1 in the arterioles and capillaries of the spinal cord. Twenty-seven adult mongrel cats were used to study vascular corrosion casts at the lumbosacral spinal cord segments immunohistologically and through scanning electron microscopic observations. Sections of the spinal cord were stained with monoclonal anti-a actin and endothelin-1 antibodies.Vascular corrosion casts demonstrated two types of vasomotion: a sausage-like peristalsis and a ring-shaped vasoconstriction at the arteriole and capillary levels. In the immunohistological study, a actin and endothelin-1 were identi®able in the vascular wall at the bifurcation, and pericytes were found to contain micro®laments of a actin. The ringshaped vasoconstriction might be regulated by smooth muscle cells in arterioles and by pericytes in capillaries by releasing endothelin-1.

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“…pericytes and astrocytic endfeet at the capillary. The processes of the pericytes, in contrast to those of the SMCs, are oriented along the axis of the blood vessels, while shorter circumferential processes surround the vascular wall (Nehls and Drenckhahn, 1993;Zimmermann, 1923).…”

Section: Pericytesmentioning

confidence: 99%

Control of Brain Capillary Blood Flow

Itoh

Suzuki

2012

J Cereb Blood Flow Metab

129

131

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While it has been widely confirmed that cerebral blood flow is closely coupled with brain metabolism, it remains a matter of controversy whether capillary flow is directly controlled to meet the energy demands of the parenchyma. Since the capillary is known to lack smooth muscle cells, it has generally been considered that capillary flow is not regulated in situ. However, we now have increasing data supporting the physiological control of capillary flow. The observation of heterogeneity in the microcirculation in vivo has suggested that intravascular factors may be involved in the flow control, including non-Newtonian rheology, red blood cell flow, leukocyte adhesion, release of vasoactive mediators, and expression of glycoproteins on the endothelial cells. Astrocytes, a key mediator of the neurovascular unit, and intrinsic innervation may also regulate capillary flow. In addition, recent findings on pericyte contractility have attracted the attention of many researchers. Finally, based on these findings, we present a new model of flow control, the proximal integration model, in which localized neural activity is detected at nearby capillaries and the vasodilation signal is transmitted proximally along the vessel. Signals are then integrated at the precapillary arterioles and other arterioles further upstream and regulate the capillary flow.

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Der Feinere Bau der Blutcapillaren

Cited by 179 publications

References 34 publications

Contractile proteins in pericytes. I. Immunoperoxidase localization of tropomyosin.

Contractile proteins in pericytes. I. Immunoperoxidase localization of tropomyosin.

Regulation of vasomotion of arterioles and capillaries in the cat spinal cord: role of α actin and endothelin-1

Control of Brain Capillary Blood Flow

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