摘要:

The microvascular changes in the wing of bats, Myoitis lucifugus, were observed during 3 weeks of normal life and 5 weeks of streptozotocin induced hyperglycemia (300–400 mg/dl, plasma). During normal life, week-to-week variations in diameter and blood flow in the same set of vessels were minor. After hyperglycemia was induced, the major initial response was dilation of all microvessels except the smallest arterioles which constricted. The dilation phase was followed by progressive constriction of all vessels. Blood flow was near normal during the dilation phase, but flow gradually decreased as hyperglycemia continued and vasoconstriction occurred. The ability to repeatedly observe the same set of microvessels on a week-to-week basis and the absence of anesthesia may make the diabetic bat a useful model in which to study the early phases of microvascular pathology during chronic hyperglycemia, which begins abruptly in adult life. In addition, the sequence of microvascular changes during chronic hyperglycemia in the bat are qualitatively similar to those in other diabetic mammals, including ma

ISSN:1018-1172    

DOI:10.1159/000158474

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Our purpose was to measure how structurally coordinated is the network of muscle cells in the brain artery. Vessels from 7 autopsies were fixed with glutaraldehyde and formalin at physiologic pressure. We embedded each artery alongside a block of liver, formed into a rectangular prism, prepared it for light microscopy and stained the sections with haematoxylin and eosin (HE). The angle of cutting the arterial segments was determined with the aid of the block of liver tissue as a Cartesian reference. We measured the directional alignment of vascular smooth muscle using the centrally located nucleus as a vector of orientation. The end coordinates of the profiles of the nuclei (appearing dark with the HE stain) were recorded on a digitizer tablet, and analysis was done as suggested by a previous modelling study. The method provides an average alignment from the collective measurements on the hundreds of nuclei in each histological section. Data from 10 arteries (approximately 22,000 nuclei) from 17 sections showed that brain arteries have highly oriented medial muscle cells aligned circumferentially (average magnitude of 1.3 ± [SD] 1.5 ° from true cross section), with a helical variation (along the artery) of ± 7.9 ° and a variation in the spiral direction of ± 5.4 °, i.e. a three-dimensional variation from nucleus to nucleus of

ISSN:1018-1172    

DOI:10.1159/000158475

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

In the isolated adventitia of rabbit aorta, blockade of neuronal uptake decreased the accumulation and deamination of 3H-/-norepinephrine (3H-l-NE) whereas blockade of extraneuronal uptake decreased O-methylation. Thus most of the O-methylation occurs in the extraneuronal elements. In the isolated media, blockade of extraneuronal uptake decreased metabolism but not accumulation of 3H-l-NE. If NE metabolism was prevented by pretreatment with pargyline and U-0521, 3H-l-NE accumulation in the isolated media increased markedly and now inhibitors of extraneuronal uptake could decrease this accumulation of 3H-l-NE by the isolated media. Thus when MAO and COMT are intact, NE does not accumulate in the extraneuronal compartment containing these enzymes, probably because it is metabolized as fast as it enters the compartment. Since the level of 3H-l-NE in the isolated media exceeded the sorbitol space when MAO and COMT were intact, some 3H-l-NE must have accumulated in a compartment which does not contain these enzymes.

ISSN:1018-1172    

DOI:10.1159/000158476

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The histometric method is often used in hypertension studies in order to reconstruct, from cross-sectional profiles of vessels in the contracted state, a hypothetical relaxed state of the vessels based on the measured length of the internal elastic lamina (IEL). In this study, the accuracy of the histometric method was tested by comparing values obtained with the histometric method from contracted vessels versus values from morphometric measurements of vessels of the same calibre but maximally relaxed. Mesenteric arteries from spontaneously hypertensive and normotensive Wistar-Kyoto rats were used. We found that the lumen size of the vessels was dependent on the methods of measurement and preparation. Lumen size, determined with the histometric method from contracted vessels, tended to be underestimated mainly because the IEL became shortened during contraction of the vessels. When vessels were prepared by perfusion fixation, a high perfusion flow rate (7.6 ml/min) caused expansion of the lumen in muscular (lumen diameter 120–250 µm) and arteriolar vessels (40–100 µm), but not in the elastic arteries (400–700 µm). The cross-sectional area of the vessel wall, however, remained unchanged when the vessels were either contracted with norepinephrine or expanded with high transmural pressure, so morphometric measurements of the vessel wall and its components can be done on both contracted and relaxed vessels. Our results suggest that the use of the histometric method for the estimation of relaxed lumen size from the contracted vessels is of very limited value. We also suggest that, for an accurate comparison of vessel wall dimensions between hypertensive and ñormotensive animals, cross-sectional area should be used instead of wall thickn

ISSN:1018-1172    

DOI:10.1159/000158477

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Relaxation of the rat thoracic aorta induced by sodium nitroprusside, 8-bromo-cyclic GMP and cyclic nucleotide phosphodiesterase inhibitor M & B 22,948 was inhibited by exposure to K+-free solution and ouabain in a concentration-dependent manner. Relaxation occurring with the change in potassium concentration in media from 1 to 2 to 10 mM was increased by sodium nitroprusside, 8-bromo-cyclic GMP and M & B 22,948. Thus, agents and procedures known to decrease and increase the activity of the Na+, K+-pump, and presumably alter the membrane potential, inhibited and enhanced relaxation, respectively. Exposure to 1 mM K+ solution increased the relaxation to low concentrations of sodium nitroprusside, but had no effect on relaxation induced by 8-bromo-cyclic GMP or M & B 22,948. Thus, another procedure which inhibits the Na+, K+-pump enhanced the effect of low concentrations of sodium nitroprusside on relaxation. Ouabain had no effect on sodium nitroprusside-induced accumulation of cyclic GMP. These results suggest that sodium nitroprusside may induce relaxation through cyclic GMP formation, effects on the Na+, K+-pump and/or hyper-polarization of the smooth muscle cell membrane.

ISSN:1018-1172    

DOI:10.1159/000158478

出版商:S. Karger AG    

年代:1983

数据来源: Karger

ISSN:1018-1172    

DOI:10.1159/000158479

出版商:S. Karger AG    

年代:1983

数据来源: Karger