The Effect of Age on the Elasticity of the Major Brain Arteries

Busby, Douglas E.; Burton, Alan C.

doi:10.1139/y65-018

Cited by 52 publications

(34 citation statements)

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“…We still have no clear idea why we have failed to duplicate the results of Scott et al 8 The difference could be due to differences in age, differences in degree of atherosclerosis, Ordinary (-test before first pressure subjection in < 40 yr. group; N = number of arterial segments; x -the mean of the groups; <rx = standard deviation of the means; crx = standard error of the mean; p = probability; No significant difference. differences in arteries chosen, or a variety of other factors."…”

Section: Discussionmentioning

confidence: 80%

Effects of high static pressures on human cerebral arteries in vitro.

Cope¹,

Roach²

1977

Stroke

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Effects of High Static Pressures on Human Cerebral Arteries in VitroTHERE IS INCREASING EVIDENCE that human intracranial saccular aneurysms are acquired rather than congenital. 1 Hassler* and NystrOm 8 have both stressed the importance of elastin fragmentation in aneurysms, and it seems likely that a break in the internal elastic membrane at the apex of an intracranial bifurcation may be the factor which initiates the development of an aneurysm. While Ferguson and Roach 4 postulated that some hemodynamic force caused the fragmentation, this has not been proven. Scott et al. 6 showed clearly that the elastic properties of human cerebral arteries and aneurysms were different, and that the elastin part of the curve (i.e. the low pressure part) was absent in aneurysms. They also found, in a few arteries, that repeating the pressure-volume curves more than three times appeared to change the elastic properties of the artery to elastic properties more like those of an aneurysm. Since

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Section: Discussionmentioning

confidence: 80%

Effects of high static pressures on human cerebral arteries in vitro.

Cope¹,

Roach²

1977

Stroke

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“…Tendon, when strained by small degrees along its load-bearing axis, shows a microscopical straightening of the low-amplitude wavy collagen fibres in accordance with the known me chanical behaviour relating resisting force to elongation [29,30], Applying these same concepts to the artery' wall distended by pressure, we would anticipate an increased coherence of alignment with pressure accompanied by a realignment of fibres along the circumferential direction. These expectations have an experimental basis from early research on the mechanics of human brain arteries [31]. From a theoretical perspective a segment of thin-walled artery, cannulated at one end and free to expand and elon gate, has a wall that is loaded in two tangential directions by the distending pressure, the average circumferential stress being twice the average longitudinal stress [32,33].…”

Section: Discussionmentioning

confidence: 99%

Three-Dimensional Collagen Organization of Human Brain Arteries at Different Transmural Pressures

Finlay

McCullough

Canham³

1995

J Vasc Res

162

124

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Measurements on the directional organization of collagen are necessary for relating the structure and mechanical function of blood vessels. The birefringent optical property of collagen has enabled us to assess the collagen architecture for brain arteries, which are prone to spasm and aneurysm formation. Using the universal stage and polarizing microscope, we measured the three-dimensional organization of the collagen of the main layers of the artery wall, and examined the effect of distending pressure on that organization. Adult arteries obtained from autopsy were fixed at one of three distending pressures, 30, 120 and 200 mm Hg; they were embedded in paraffin and sectioned parallel to the vessel axis at 4 µm thickness. Sections were stained with picrosirius red, a birefringent enhancement stain specific for collagen. Orientation data were obtained from tangential sections from thirteen arteries. We chose to use tangential sections that graze the curving surface of individual layers, to permit measurements that are equally sensitive to fibres in the mechanically meaningful range of directions including longitudinal, helical and circumferential. Each measurement was from a single fibre or group of fibres at a specific location; the mean direction and its variation of alignment within each artery layer were calculated. In some arteries, the adventitia and subendothelium measurements were separated into sublayers, distinguishable by the birefringent optical appearance. Main findings included a substantial component of longitudinal fibres in the adventitia and subendothelium, highly varied in coherence and mean direction, and a thin collagen layer of the adventitia, radially outside the medial muscle cells, that was highly organized circumferentially (circular standard deviation of 9°). At higher pressures, the collagen fabric of all the layers was increasingly coherent and more circumferential in direction.

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“…2 This problem may be increased in aged subjects as collagen forma tion increases and elasticity decreases in vascular tis- sue. [6][7][8][9] Lundgren et al 18 and Weiss 19 reported that low ering the blood pressure of hypertensive rats will partially or totally reverse the hindlimb vascular changes produced by the hypertension and improve the perfusion parameters of this tissue. Warshaw et al 20 reported that 23 weeks of antihypertensive drug ther apy lowered resistance vessel smooth muscle cell con tent in SHR in direct proportion to the reduction in blood pressure.…”

Section: Discussionmentioning

confidence: 99%

“…Initiation of hyalin incorporation and loss of vascular elasticity. [6][7][8][9] treatment was staggered so that an equal number of rats This is supported by reports that maintenance of CBF from each group completed the treatment regimen and and CMR02 during hypotension is complicted by ag could be tested each week. ing and hypertension.…”

mentioning

confidence: 91%

The influence of antihypertensive therapy on cerebral autoregulation in aged hypertensive rats.

Hoffman¹,

Miletich²,

Albrecht³

1982

Stroke

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SUMMARY Cerebrovascular responses to hemorrhage induced hypotension were tested in aged (24 month) spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto (WKY) after ten weeks of antihypertensive drug or sham treatment. Antihypertensive drug treatment consisted of 1 mg/kg/day minoxidil, 4 mg/kg/day hydralazine and 4 mg/kg/day propranolol given in the drinking water. Antihyper tensive therapy produced a 30% decrease in systolic blood pressure in aged SHR to levels not significantly different from sham treated WKY. Cerebral blood flow (CBF), measured under control conditions using ketamine anesthesia, was not significantly different between sham and drug treated SHR and WKY. Cerebral oxygen metabolic rate (CMR02) was significantly decreased in drug treated SHR and WKY compared to sham treated rats. Lowering blood pressure to a level between 80 and 95 torr produced no significant change in CBF or CMR02 in sham or drug treated WKY or antihypertensive treated SHR, but a produced a significant decrease in both CBF and CMR02 in sham treated SHR. Decreasing mean blood pressure to 50-60 torr produced a significant decrease in CBF but not CMR02 in both WKY treatment groups and in antihypertensive treated SHR, but again in sham treated SHR both CBF and CMR02 were significantly decreased. These results indicate that aged hypertensive rats are unable to maintain CBF or CMR02 under even moderate hypotensive test conditions, but that cerebral autoregulation can be im proved with antihypertensive therapy.Stroke, Vol 13, No 5, 1982 STUDIES HAVE SHOWN that chronic hypertension trolled oven for pressure measurement. SHR and produces cerebrovascular changes which produce a WKY receiving antihypertensive therapy were given shift in cerebral autoregulation and inhibit the ability of the following drugs: minoxidil (1 mg/kg/day), hydral hypertensive subjects to maintain cerebral blood flow azine (4 mg/kg/day), propranolol (4 mg/kg/day). The (CBF) and cerebral oxygen metabolism (CMR02) drugs were added to the drinking water with the con during hypotensive stimuli. [1][2][3][4][5] This problem may be centration adjusted to the daily intake of the rat. Four increased in the aged hypertensive subject due to struc test groups were chosen with 15-20 rats per group. tural vascular changes such as atherosclerosis develop SHR and WKY received either ten weeks of antihyper ment, increased collagen formation, intimal fibrinotensive drug or sham (water) treatment. Initiation of hyalin incorporation and loss of vascular elasticity. [6][7][8][9] treatment was staggered so that an equal number of rats This is supported by reports that maintenance of CBF from each group completed the treatment regimen and and CMR02 during hypotension is complicted by ag could be tested each week. ing and hypertension.1 ' 10, " Little is known concerning the effect of antihypertensive therapy on cerebral au Surgery toregulation in aged hypertensive subjects. It is impor At the end of the ten week drug or sham treatment tant to determine whether antihype...

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The Effect of Age on the Elasticity of the Major Brain Arteries

Cited by 52 publications

References 0 publications

Effects of high static pressures on human cerebral arteries in vitro.

Effects of high static pressures on human cerebral arteries in vitro.

Three-Dimensional Collagen Organization of Human Brain Arteries at Different Transmural Pressures

The influence of antihypertensive therapy on cerebral autoregulation in aged hypertensive rats.

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