ISSN:0030-3755    

DOI:10.1159/000310718

出版商:S. Karger AG    

年代:1996

数据来源: Karger

ISSN:0030-3755    

DOI:10.1159/000310719

出版商:S. Karger AG    

年代:1996

数据来源: Karger

ISSN:0030-3755    

DOI:10.1159/000310720

出版商:S. Karger AG    

年代:1996

数据来源: Karger

ISSN:0030-3755    

DOI:10.1159/000310721

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

Blood flow autoregulation may be deficient in patients with glaucoma, making the optic nerve circulation susceptible to the challenge of intraocular pressure (IOP). Adequacy or inadequacy of autoregulation may be a factor that decides whether a patient with elevated IOP develops glaucomatous optic nerve damage. Hypothetically, capillaries may assist arteries and veins in the regulation of blood flow. Our attention has become focused on the pericytes, particularly abundant in the optic nerve and retina, which are a contractile component of capillaries and may therefore be the cells responsible for the capillary’s role in autoregulatio

ISSN:0030-3755    

DOI:10.1159/000310722

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

As cell cultures of pericytes derived from bovine retina are in regular use by a number of investigators, we decided to confirm the identity of these cells, to show them different from other cells that might contaminate cultures derived from retinal tissue, to characterize the properties they share with pericytes in situ and to establish a practical and effective means for confirmation of the cell type of each batch of cultured cells used in scientific studies. Cultured pericytes differed in immunocytochemical reactions and phagocytic properties from vascular smooth muscle, vascular endothelial cells, astroglia, conjunctival fíbroblasts or retinal pigment epithelium. Like vascular smooth muscle, pericytes in situ and those in culture have the contractile proteins actin and myosin, which implies a potential role in blood flow control. In routine studies of cultured pericytes, they can be identified by their unique reaction in situ and in vitro with the antiganglio-side monoclonal antibody 3G5. The presence of any contaminating endothelial cells can be recognized by their ability to take up acetylated low-density lipoprotein

ISSN:0030-3755    

DOI:10.1159/000310723

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

To test the potential for vasoactive neuropeptide receptors to affect capillary resistance, we have begun to study the plausibility that pericytes might be equipped to respond to a representative peptide vasoconstrictor and a representative peptide vasodilator. Pericytes cultured from the bovine retinal vasculature specifically bind the angiotensin II (Ang II) antagonist saralasin (1 nM125I-saralasin bound at 2.2 ± 0.41 fmol/mg protein) and 125I-vasoactive intestinal peptide (VIP; Kd of 0.5 nM with a population of 30 fmol/mg protein). Incubation with 100 µM Ang II induced minimal cAMP synthesis, while VIP (1 µM, 10 µM) did not induce any change in cAMP concentration. Ang II (10 µM and 100 µM) caused contraction of pericytes cultured on an elastic silicone surface. Circulating or locally produced vasoactive neuropeptides might affect pericyte contractile tone via several intracellular pathways, moderated by indirect effects of these peptides through endothelial stimulation, with the net effect on local blood flow resulting from the effects on arteries and veins as well as capill

ISSN:0030-3755    

DOI:10.1159/000310724

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

To characterize the relaxation of pericytes induced by β-adrenergic stimulation, changes in the contractile tone of pericytes were quantified as a change in the wrinkling of an elastic silicone surface on which they were cultured. Isoproterenol produced relaxation of pericytes in a dose-dependent manner over a range of 5 nMto 1 µM. Low concentrations of the nonselective β-blockers propanolol and timolol blocked the relaxation produced by isoproterenol. The specific β2-adrenergic component of isoproterenol-induced relaxation was shown by blockage with bromoacetyl alprenolol menthane. In contrast, atenolol and betaxolol, as relatively selective β1-adrenergic blockers, had no effect on the isoproterenol-induced relaxa

ISSN:0030-3755    

DOI:10.1159/000310725

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

We undertook this study to determine if pericytes respond to carbon dioxide in a manner such that they could help control capillary blood flow and that their physiologic responses to pCO2 might be worthy of detailed study. Pericytes were isolated from bovine retinas and grown in cell culture. Changes in the contractile tone of the pericytes upon changing the ambient pCO2 were observed by noting changes in the wrinkling of an elastic silicone surface on which they were grown. An increase in pCO2 caused acidosis of the medium and relaxation of the pericytes in a reversible, concentration-dependent manner. These findings suggest that the regulation of blood flow to meet local metabolic needs does not reside entirely in the arterioles and precapillary sphincters, but at least in part in the capillary bed through the contractile properties of pericytes. The local pCO2 is one of several potential indicators of whether or not local blood flow is adequate for local tissue needs. The response to local conditions may modulate or be modulated by the effect of neurotransmitters and hormones on the local rate of blood flow.

ISSN:0030-3755    

DOI:10.1159/000310726

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

The subject of the blood supply of the optic nerve head (ONH) is reviewed briefly. The circulation of the posterior ciliary artery is the main source of blood supply to the ONH, except for the surface nerve fiber layer which is supplied by the retinal circulation. The blood supply in the ONH is sectoral in nature, which is the reason why there is the sectoral involvement of the ONH in its ischemic disorders. It is essential to understand that the pattern of blood supply in the ONH shows marked interindividual variation, and so consequently does the pattern of visual loss in its ischemic disorders. The venous drainage from the ONH is by the central retinal vein. Reasons for various controversies on the subject are discussed.

ISSN:0030-3755    

DOI:10.1159/000310727

出版商:S. Karger AG    

年代:1996

数据来源: Karger