摘要:

Control of intracellular Ca2+ ([Ca2+]i) is critical to vascular smooth muscle function. Calcium channels are the major route by which Ca2+ enters the smooth muscle cell. This article reviews the types of calcium channel present in vascular smooth muscle cells and their physiological and biochemical regulation.

ISSN:1018-1172    

DOI:10.1159/000159111

出版商:S. Karger AG    

年代:1995

数据来源: Karger

摘要:

Viable and non-viable cells in coronary and internal thoracic arteries, collected at autopsy 7-24 h post-mortem from individuals 15-81 years of age, were detected using the fïxable fluoroprobes 5-chloromethylfluorescein diacetate (green) and ethidium homodimer-1 (orange/red). Viability status of individual endothelial and smooth muscle cells was confirmed by simultaneous autoradiographic detection of incorporated [3H]glucosamine. Twenty-five percent of coronary and 42% of internal thoracic arteries contained viable cells up to 24 h following death. For the majority of viable vessels the mean percentage of viable cells ranged between 60 and 80% with no significant difference between coronary and internal thoracic arteries and no relationship with either age of the donor or with time to autopsy. Non-viable cells were usually distributed fairly evenly amongst viable cells but this pattern could not be assumed. In a number of vessels non-viable cells were variably clustered in different regions of vessel wall. These findings confirm that vessels sampled at autopsy can be used for metabolic studies with the caveat that assessment of cell viability is a necessary prerequisite for interpretation of results

ISSN:1018-1172    

DOI:10.1159/000159112

出版商:S. Karger AG    

年代:1995

数据来源: Karger

摘要:

This study utilised catecholamine fluorescence histochemistry, multiple-labelling immunohistochemistry and retrograde axonal transport to determine the distribution and neuropeptide content of sympathetic neurons innervating veins in the dorsal skin of the guinea pig pinna. There was a dense plexus of sympathetic axons innervating the large central vein at the base of the ear and the adjoining maxillary vein. The density of the plexus decreased towards the distal margin of the ear and in smaller veins, and was very sparse in the lateral veins at the base of the ear. Small venules 90%) of the TH-IR axons in small and large veins also contained IR to dynorphin-related peptides. Thus, sympathetic venoconstriction in the thermoregulatory bed of the guinea pig pinna is likely to occur predominantly in the large central veins towards the base of the ear. Furthermore, sympathetic constriction is likely to be qualitatively different in large cutaneous veins from that occurring in small veins, and absent altogether from small venules and some lateral

ISSN:1018-1172    

DOI:10.1159/000159113

出版商:S. Karger AG    

年代:1995

数据来源: Karger

摘要:

The main objective of this work was to study the role of potassium channels in the cholinergic relaxation of cutaneous arteries during cooling. Acetylcholine (10–8–10–4M) produced isometric concentration-dependent relaxation of precontracted segments of rabbit ear (cutaneous) and femoral (noncutaneous) arteries; this relaxation was higher at 24 ° C (cooling) than at 37 °C in ear, but not in femoral, arteries. In both types of arteries, at 37 and 24 °C, the relaxation to acetylcholine was partially reduced by the inhibitor of nitric oxide synthase NG-nitro-L-arginine methyl ester (L-NAME, 10–4M), and the relaxation that remained after L-NAME was higher at 24°C than at 37°C in ear, but not in femoral, arteries. At 37 and 24°C, the persistent relaxation to acetylcholine after L-NAME was further reduced by smooth muscle depolarization with medium containing a high concentration of potassium (6 × 10–2M), and with the nonspecific inhibitors of potassium channels tetraethylammonium (10–2M) or 4-aminopyridine (5 × 10–3M) in both ear and femoral arteries. In ear arteries, the inhibitor of high conductance calcium-activated potassium channels charybdotoxin (10–7M), alone or combined with L-NAME, reduced the relaxation to acetylcholine at 24°C, but not at 37°C. In femoral arteries, charybdotoxin alone did not modify, but combined with L-NAME reduced, the relaxation to acetylcholine at either temperature. At 37 and 24 °C, the inhibitor of low conductance calcium-activated potassium channels apamin (10–7 M), the inhibitor of ATP-dependent potassium channels glibenclamide (10–5M) and the cyclooxygenase inhibitor meclofenamate (10-5M), alone or combined with L-NAME, did not modify the relaxation of both ear and femoral arteries to acetylcholine. These results suggest: (1) the cholinergic relaxation of cutaneous (ear) and noncutaneous (femoral) arteries could be mediated by endothelial nitric oxide and by activation of potassium channels, and (2) cooling increases the relaxation of cutaneous arteries to cholinergic stimulation, which may be mediated, in part, by an increased

ISSN:1018-1172    

DOI:10.1159/000159114

出版商:S. Karger AG    

年代:1995

数据来源: Karger

摘要:

When ring segments of artery free of external loads are cut longitudinally, they spring open. This property, which has been termed residual strain, is a manifestation of an underlying residual stress and may be quantified by measuring the degree to which the cut ring springs open. Residual stress serves to redistribute the forces in the media and to minimize the stress gradient between its inner and outer margins. Its magnitude and distribution are closely related to vascular growth and development. We have measured the degree of opening (in terms of an opening angle, see below for its definition) in 168 rings removed from six positions along aortae obtained at autopsy from 30 subjects aged between 3 months and 87 years. At all ages, there was an overall increase in opening angle along the aorta away from the heart. At all positions, the opening angle increased with age and was higher in vessels with visible atheroma. At all ages, the opening angle was significantly greater in males than in females. This difference persisted when allowance was made for the greater incidence of atheroma in males. We have found a similar age-related increase in rats, although there was no difference between males and females. These observations are consistent with a recently proposed ‘stress-growth’ law in which remodelling of the arterial wall is driven by the non-uniform distribution of stress across it and may be associated with known sex-related differences in the aetiology of cardiovascular dise

ISSN:1018-1172    

DOI:10.1159/000159115

出版商:S. Karger AG    

年代:1995

数据来源: Karger

摘要:

Our previous study demonstrated that high potassium (K) diets reduce stroke mortality in stroke-prone spontaneously hypertensive rats (SHRsp) even when the blood pressure is not lowered. On the other hand, macrophage infiltration into the vascular wall is known to play an important role in the development of arterial lesions. In this study, in vivo and in vitro experiments were performed to examine the effect of high K diets on macrophage adherence to the vascular wall in SHRsp rats. In the in vivo study, 51Cr-labelled macrophages, collected from the peritoneal cavity, were injected intravenously to SHRsp rats fed 6% high NaCl diets containing either normal 0.5% K or high 2.1 % K, and, 45 min later, the rats were perfused with buffered saline to remove blood. Radioactivity from macrophages in the aorta was 40% lower in the high K SHRsp than in the normal K SHRsp (p < 0.002), and the brain of high K SHRsp also showed a 52% lower macrophage radioactivity than that of normal K SHRsp (p < 0.007). Although the mean blood pressure was slightly lower in the high K diet group than in the normal K diet group (167 vs. 184 mm Hg), these differences remained still prominent even when we compared groups with matching blood pressures; –33% for the aorta (p < 0.02) and –55% for the brain (p < 0.02). In the in vitro study, the aortas of SHRsp rats similarly fed on normal or high K diet were excised and mounted in a perfusion chamber. They were perfused with labelled macrophages at normotensive or hypertensive pressure. In normal K SHRsp, macrophage radioactivity remained in the washed aorta was 158% higher in high perfusion pressure group than in normal pressure (p < 0.002). However, they did not significantly differ between two perfusion pressures in high K SHRsp. These results indicate that high K diets reduce endothelial injuries which allow adherence and infiltration of macrophages into the vascular wall of hypertensive animals, and thereby contribute to the reduction of vascular lesions and stroke mortal

ISSN:1018-1172    

DOI:10.1159/000159116

出版商:S. Karger AG    

年代:1995

数据来源: Karger

摘要:

The infusion of physiological salt solution into the lumen of ring segments of the isolated rabbit facial vein induces an increase in vessel wall tone. Changes in 22Na+ and 45Ca2+ net uptake as well as 22Na+ unidirectional efflux in response to flow in this vessel were compared to the response to histamine (1 µM) and to angiotensin II (0.1 µM). 22Na+ net uptake per unit force developed in response to flow was 7.9-fold greater than that for histamine (1 µM) and twice that for angiotensin II (0.1 µM). In comparison, 45Ca2+ net uptake per unit force in response to flow, histamine and K+ were similar. Flow-induced contraction and the related 45Ca2+ and 22Na+ net uptake were decreased by amiloride (30 µM) and methyl isobutyl amiloride (30 µM) without changes in 45Ca2+ or 22Na+ net uptake per unit force. Ouabain (10 µM) enhanced flow-induced contraction and the related 22Na+ net uptake. Both ouabain (10 µM) and Bay K 8644 (1 µM) increased flow-induced contraction and the related 45Ca2+ net uptake whereas they decreased the 45Ca2+ net uptake per unit force. Flow, histamine and angiotensin II increased the unidirectional efflux of 22Na+. This increase in 22Na+ unidirectional efflux was attenuated by ouabain (10 µM). These experiments demonstrate that the increases in wall force due to flow, histamine and angiotensin II are associated with increases in 22Na+ net uptake and unidirectional efflux. Flow preferentially promotes the entry of Na+, compared to histamine and angio

ISSN:1018-1172    

DOI:10.1159/000159117

出版商:S. Karger AG    

年代:1995

数据来源: Karger

ISSN:1018-1172    

DOI:10.1159/000159118

出版商:S. Karger AG    

年代:1995

数据来源: Karger

ISSN:1018-1172    

DOI:10.1159/000159119

出版商:S. Karger AG    

年代:1995

数据来源: Karger

ISSN:1018-1172    

DOI:10.1159/000159120

出版商:S. Karger AG    

年代:1995

数据来源: Karger