摘要:

The vascular endothelium is now recognized as an important organ in the non-neural regulation of vascular tone. In particular, it is now well established that endothelial cells release various paracrine factors that relax as well as contract vascular smooth muscle cells. The relaxing factors include endothelium-derived relaxing factor (EDRF), which has been demonstrated to be nitric oxide or a nitric oxide-containing compound, prostacyclin (PGI2) and endothelium-derived hyperpolarizing factor (EDHF). The chemical properties and nature of EDHF are still unknown. Endothelial cells also release vasoconstrictor peptides, the endothelins, which increase smooth muscle Ca2+concentration, resulting in potent vasoconstriction. Since the formation of all these endothelium-derived factors is due to changes in endothelial free Ca2+, the main purpose of the present review is to summarize current knowledge of the underlying molecular mechanisms involved in agonist-induced Ca2+regulation and the mechanisms by which endothelial Ca2+concentrations regulate the formation of endothelium-derived vasoactive factors.

ISSN:1062-3329    

DOI:10.3109/10623329409100960

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

Both endocardial endothelium and coronary vascular endothelium in the heart influence myocardial contraction by releasing diffusible agents that affect the subjacent myocardium. This effect of cardiac endothelium can be demonstrated both in isolated tissue preparations as well as pump function in intact hearts bothin vitroandin vivo. Agents released by endocardial endothelium include both nitric oxide (NO) and an unidentified‘contraction-prolonging substance’(‘endocardin’) that respectively decrease and increase the duration of twitch contraction, probably by altering myofibrillar calcium sensitivity. The endothelium of the coronary vasculature also releases NO, with similar effects on contraction, and in addition releases several other unidentified agents. The potential physiological and pathophysiological roles of all of these agents have yet to be fully elucidated and are an important and expanding new area of cardiovascular research that could lead to novel therapeutic possibilities.

ISSN:1062-3329    

DOI:10.3109/10623329409100961

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

The action of interleukin-1 alpha (IL-1α) and tumor necrosis factor alpha (TNFα) on the production of biologically active granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) was studied and the secretion into the supernatant of human endothelial cell cultures was quantified by enzyme-linked immunosorbent assay (ELISA). In unstimulated endothelial cells low concentrations of G-CSF and GM-CSF were measured by ELISA. Stimulation for 24 h with either IL-1αor TNFαcaused a concentration-dependent increase of both colony stimulating factors in the supernatant. Range of IL-1αstudied: 0.1–100 U/ml; maximum CSF induced: G-CSF 142 + 16 ng/6×105cells, GM-CSF 18.5±3.3 ng/6×105cells. Range of TNFαstudied: 10–2000 U/ml. 4 maximum CSF induced: G-CSF: 36±6 ng/6×105cells, GM-CSF 16.7±1.5 ng/6×10 cells. The dosages of both factors were varied to study the combined action of IL-1αand TNFαon CSF production. IL-1α(0.1–10 U/ml) combined with TNFa (10–1000 U/ml) enhanced the effect onCSFproductionina superadditivemannercomparedwith theeffect of TNFaorIL-1αalone. Higher concentrations of IL-1α(10 U/ml) with TNFa (10–1000 U/ml) inhibited G-CSF production but not GM-CSF production. IL-1αwas more potent as an inducer of G-CSF than TNFa at doses approximately equipotent in causing GM-CSF production in human endothelial cells. Quantitative determination of G-CSF and GM-CSF revealed that the production of these CSFs was differently regulated by IL-1αand TNFαand demonstrated a superadditive effect by the two cytokines on G-CSF and GM-CSF production.

ISSN:1062-3329    

DOI:10.3109/10623329409100962

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

The effects of hypoxia on endothelin-1 (ET-1) release were studiedin vitroin human, sheep (under resting force) and preconstricted rabbit pulmonary artery rings. Hypoxic contraction in human and sheep arteries was well maintained, while that in rabbit arteries was transient and followed by vasorelaxation. The basal production of ET-1, measured by radioimmunoassay in Krebs solution, was not affected by hypoxia in human pulmonary arteries (control, 0.71±0.16vshypoxia, 0.73±0.41 fmol ml−120 min−1). Similarly, hypoxia did not produce any change in the levels of ET-1 released by sheep pulmonary artery rings. In the latter preparation, the role of hypoxia in ET-1 release was characterized in either the early or the late phase of the contraction, and no significant change was observed (control, 26.52±6.36, hypoxia early phase, 19.06±5.82 and hypoxia late phase, 26.4±9.03 fmol ml−115 min−1). In rabbit pulmonary arteries hypoxia also failed to stimulate ET-1 release (control, 2.28±0.85, hypoxia, 5.95±3.27 fmol ml−115 min−1). Basal ET-1 release can be seen to be significantly greater in sheep than in human pulmonary artery rings under oxygenated conditions. These results suggest that ET-1 is not the mediator regulating pulmonary artery contraction during acute hypoxia.

ISSN:1062-3329    

DOI:10.3109/10623329409100963

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

Renal glomeruli isolated from Wistar rats were incubated with substances that modify nitric oxide (NO) synthesis in the presence of the phosphodiesterase inhibitor IBMX and glomerular cGMP production was measured by radioimmunoassay. Glomeruli incubated in basal conditions produced 0.15±0.02 pmol cGMP/mg protein. Acetylcholine (0.1μM) and bradykinin (0.1μM) increased cGMP production by 113% and 183%, respectively. N-nitro-L-arginine-methyl ester (L-NAME) (0.1 mM), a NO synthetase inhibitor, completely blocked the increase induced by acetylcholine or bradykinin. L-NAME or methylene blue (1μM) alone had no significant effect on basal cGMP production. L-arginine (1μM) increased glomerular cGMP production approximately fourfold. Maximal cGMP stimulation (about sixfold) was obtained with ANP 0.1μM. Endothelin also increased cGMP production (65%), this action being blocked by L-NAME. These data suggest that NO can be synthesized in glomerulus and that NO stimulates soluble guanylate cyclase to modulate glomerular function.

ISSN:1062-3329    

DOI:10.3109/10623329409100964

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

Exposure of precontracted vascular tissues to anoxiain vitrocauses a rapid but short lasting additional contraction of vascular smooth muscle. To determine the effect of sustained anoxia on vascular reactivity, quiescent rat aortic rings were equilibrated at 37°C under 95% O2(normoxia) or 95% N2(anoxia) for 15 min. The rings were then contracted with norepinephrine (NE) or the TxA2-endoperoxide analog 1146,619. The response of aortic rings to the endothelium-dependent vasorelaxant stimuli acetylcholine (ACh) and calcium ionophore A23,187, the endothelium-independent stimuli nitroglycerin (NTG) and sodium nitroprusside (SNP) and the nitric oxide-independent stimulus isoproterenol (ISO) was also examined. Vascular contraction was markedly decreased in anoxic rings (P<0.01versusnormoxic rings) in response to both NE and U46.619 and was not modified on treatment with indomethacin, L-NMMA or Nω-L-arginine. Relaxation of anoxic rings was also markedly impaired (P<0.01) in response to the endothelium-dependent vasorelaxants ACh and calcium ionophore A23,187. Rings treated with ACh showed much less cyclic GMP accumulation during anoxia than during normoxia (P<0.02), indicating decreased EDRF synthesis during anoxia. The degree and rate of relaxation of anoxic rings in response to the endothelium-independent vasorelaxants NTG and SNP were also markedly diminished (P<0.01versusnormoxic rings) although cyclic GMP accumulation in anoxic rings treated with NTG was the same as in normoxic rings, suggesting diminished tissue sensitivity to cyclic GMP. Relaxation in response to ISO in anoxic rings was also markedly decreased. These observations indicate that reduced endogenous EDRP synthesis and tissue sensitivity to cyclic GMP and cyclic AMP-dependent relaxants are involved in the anoxia-associated decrease in vasorelaxation.

ISSN:1062-3329    

DOI:10.3109/10623329409100965

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

Endothelin-1,−2, and−3 (ET-1,−2,−3) and their precursors, the big endothelins (big ET) are a family of novel endothelium derived vasoconstrictor peptides. Concentrations varying between 0.1–48 fmol·ml−1have been reported for ET-1 in the plasma of normal human subjects whereas little is known as yet about ET-3 and big ET concentrations in plasma. We have evaluated and optimized the radioimmunological determination of human ET-1, ET-3 and big ET-1 with respect to the mode of extraction of these peptides from plasma, buffer conditions and non-ionic detergents. It was shown that each of these factors could adversely affect the amounts of immunoreactive ET-1 detected in plasma, whereas immunoreactive ET-3 and big ET-1 concentrations were less influenced by these assay conditions. For the first time, the concentrations of immunoreactive ET-1 determined in plasma after silica gel extraction were confirmed by a radio receptor assay and by specific immunoextraction. The wide variety of ET-1 concentrations reported so far for plasma from normal human subjects can be explained to a high extend by these findings.

ISSN:1062-3329    

DOI:10.3109/10623329409100966

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

Mouse cerebral arterioles studiedin vivodemonstrated endothelium dependent responses to adenosines-diphosphate (ADP),αβmethylene adenosine triphosphate (αβMATP), 2 methyl thio adenosine triphosphate (2MeSATP), and endothelium independent dilation to 2 chloroadenosine (2-CA). Endothelium dependence was directly established by markedly inhibiting the response with focal endothelial injury produced by a light/dye technique. Based on the effects of cyclooxygenase inhibitors and N guanidino-L-monomethyl arginine on the responses it appears that the response to ADP and 2MeSATP are mediated by both a prostanoid liberated from the endothelium and by classical endothelium derived relaxing factor (EDRF) whileαβMATP is mediated by EDRF alone. Based on the effects of 8 phenyl theophylline (8 PT) on the responses it appears that a type A receptor in the vascular smooth muscle is responsible for the endothelium independent dilation produced by 2-CA. The 8 PT failed to influence the response to ADP orαβMATP. The lowest doses ofαβMATP and 2MeSATP produced endothelium independent constrictions. 8 PT inhibited the dilations produced by 2 MeSATP, a result which we could not explain.

ISSN:1062-3329    

DOI:10.3109/10623329409100967

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

The effects of the calcium channel blockers S- and R-verapamil or Ro 40-5967 on penetration processes of peripheral blood lymphocytes (PBL) added to allogenic human vascular endothelial cell (HUVEC) monolayers were studied. Both PBL adhesion and migration were evaluated by combined phase contrast and reflection interference contrast microscopy. PBL adhesion was inhibited by 22% when 100μg/ml verapamil was added to the cell cultures. PBL migration was completely suppressed with verapamil concentrations above 80μg/ml (EC50: S-verapamil: 59.7μg/ml, R-verapamil: 52.3μg/ml). No differences were seen in the results obtained either with or without cytokine (γ-IFN or IL-1) stimulation. Ro 40-5967 redlfced adhesion completely above concentrations of 40μg/ml. EC50for migration was 13±2 or 13±1μg/ml, respectively. Immunohistochemical analysis of adhesion molecule expression on HUVEC revealed no inhibition of 1CAM-1 and VCAM-1 by verapamil or Ro 40-5967. We concluded that the effects of the calcium channel blockers did not depend on cytokine stimulation and, as they were found similar for both verapamil enantiomers, also did not depend on the calcium channel blocking properties of the compounds. Since adhesion molecule expression was not reduced on HUVEC the Ca2+-channel blockers tested in this assay seem to affect cellular infiltration via other pathways.

ISSN:1062-3329    

DOI:10.3109/10623329409100968

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

Damage to the vasculature contributes significantly to the overall pathologic consequences of acute radiation exposure. Although at least part of this damage may be accountable to inflammatory reactions involving leukocyte/endothelial interactions, little is known of post-irradiation endothelial expression of the immunologically relevant surface molecules which are intimately involved in these processes. To address this issue, we have employed immunofluorescence flow cytometry to examine the effects ofγ-radiation on the constitutive and cytokine-induced expression of HLA class I, HLA class II, and intercellular adhesion molecule-1 (ICAM-1) by cultured human endothelial cells (EC). EC were -γ-irradiated (137Cesium, 1.2 Gray [GyJ/min) in confluent monolayer at doses up to 100 Gy, treated with interferon7 (IFNγ, 200 IU/ml, 72 hr), tumor necrosis factorα(TNFα, 40 IU/ml, 24 hr), or incubated in cytokine-free medium, then harvested and reacted with fluorescein-labelled monoclonal antibodies with specificities for HLA class I, HLA class II (DR), or ICAM-1. Quantitative fluorescence flow cytometric analysis demonstrated that neither constitutive expression nor cytokine-induced upregulation of any of these surface molecules was attenuated following even the highest radiation doses (100 Gy). Similarly, induction of endothelial HLA DR expression was observed in transwell cocultures when irradiated EC were exposed to cytokines liberated by activated T cells. In contrast, cell division was completely arrested by doses in the range of 6–10 Gy, as determined by standard clonogenic assay, and D0values for EC lines used in these experiments (1.0–1.8 Gy) were consistent with those commonly reported in the literature. These studies indicate that the constitutive endothelial expression of immunologically important surface molecules, as well as the cytokine responsiveness of these cells, represent highly radioresistant functions. This suggests that endothelial cells can retain their ability to participate interactively in the inflammatory response following substantial acute radiation exposure, and supports the hypothesis that endothelial cells provide an immune/inflammatory component in the overall radiation-induced pathologic response.

ISSN:1062-3329    

DOI:10.3109/10623329409100969

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor