Elastizität und Morphologie des Aortenwindkessels beim Bluthochdruck

Karnbaum, S

doi:10.1007/bf02119174

Cited by 19 publications

(5 citation statements)

References 31 publications

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“…Under such in vivo circumstances it may, however, be difficult to settle whether the reduced distensibility reflects mainly an increased smooth muscle tone or predominantly a structural vascular change. O n the other hand, large arteries have been studied also in uitro when it is easier to control the state of smooth muscle activity and such studies, too, indicate a reduced wall distensibility in hypertension (Asteroth and Kreuziger 1951, Karnbaum 1961, .4ars 1968. Folkow and Lofving (1956) studied the distensibility of the resistance vessels proper in normotensive cats by perfusing the isolated calf with a plasma substitute and measuring the pressure-flow relationship a t various levels of smooth muscle activity, an approach largely adapted in the present study.…”

Section: Results and Commentsmentioning

confidence: 99%

The Distensibility of the Resistance Vessels in Spontaneously Hypertensive Rats (SHR) as Compared with Normotensive Control Rats (NCR)

Hallbäck

Lundgren

Weiss

1974

Acta Physiologica Scandinavica

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Earlier studies on human essential hypertension, as well as on SHR, suggest that an increased media thickness, partly encroaching upon the vascular lumen, forms the main background of the increased flow resistance in primary hypertension (e.g. Folkow et al. 1970). In the present investigation a comparison was made concerning the distensibility of the resistance vessels in order to further explore the proposed difference in vascular design. The simultaneously perfused hindquarter vessels of SHR and NCR were exposed to sudden, repeated shifts of pressure and flow, first at maximal vasodilatation and then at stable levels of smooth muscle tone, induced by barium ions or noradrenaline. Relative changes of vascular internal radius (ri) were calculated from the pressure‐flow values, assuming ri to be proportional to 4 flow conductance. For given changes in distending pressure (Pd), the SHR resistance vessels exhibited considerably smaller percentual ri changes than the NCR ones, whether starting from the same Pd, the same ri, or even when both Pd and ri were initially kept identical in NCR and SHR by exposing the SHR vessels to lower concentrations of constrictor agents. This evidence of reduced vascular distensibility in SHR was obvious both at maximal dilation and, particularly, when smooth muscle tone was increased. This strongly supports the view that especially the media component of the SHR resistance vessels is enhanced in bulk, thus markedly influencing both “active” and “passive” resistance changes.

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Section: Results and Commentsmentioning

confidence: 99%

The Distensibility of the Resistance Vessels in Spontaneously Hypertensive Rats (SHR) as Compared with Normotensive Control Rats (NCR)

Hallbäck

Lundgren

Weiss

1974

Acta Physiologica Scandinavica

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“…cocious senile alterations (11,31) since they are indistinguishable morphologically. These conclusions, based as they are solely on morphological similarities, must await confirmation from comparative chemical studies.…”

Section: Morphological Studiesmentioning

confidence: 99%

Response of the Rat Aortic Media to Hypertension

Wolinsky

1970

Circulation Research

330

150

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Clinical and experimental studies indicate that hypertension accelerates the development of arteriosclerosis. Morphological and chemical studies of the distended rat thoracic aorta were undertaken to define the structural and compositional alterations of the media which accompany hypertension and to relate these changes to increases in calculated medial stress. An 8-week period of hypertension was associated with significandy greater diameter, medial thickness, and cross-sectional area of the media of the thoracic aorta than in nonnotensive animals. Calculated wall tension was significantly higher in hypertensive animals, but the number of medial lamellar units was not greater than that usual in normotensive animals; this resulted in a strikingly elevated value for calculated tension per medial lamellar unit for the aortas of hypertensive animals. A highly significant linear relation was found between total tension and cross-sectional area of the media of the same segment. In addition, the absolute amounts of both medial elastin and collagen were increased in hypertensive animals; however, the percent of these elements remained essentially constant, indicating little change in the composition of aortic tissue. Increments in both fibrous proteins were linearly related to increases in calculated mural stress, and medial accumulations of elastin and collagen proceeded at similar rates. These findings demonstrate a linear relation among vessel dimensions and amounts of medial elastin and collagen and calculated wall tension.ADDITIONAL KEY WORDS structure-function relations elastin collagen smooth muscle vascular disease cross-sectional wall area

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“…Because baroreceptors are stretch receptors, reduced distensibility of the hypertensive aortic wall automatically lowers the receptor response to an increase of pressure. In hypertension, most arteries, including the aorta, have increased content of water, sodium and possibly other electrolytes, and because of structural changes they are less distensible than normal (Tobian 1960, Karnbaum 1961, Feigl, Peterson and Jones 1963, Greene et at. 1966, Postnov 1966.…”

Section: Mechanisms Of Resettingmentioning

confidence: 99%

Aortic Baroreceptor Activity in Normal and Hypertensive Rabbits

Aars

1968

Acta Physiologica Scandinavica

111

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AARs, H. Aortic baroreceptor activity in normal and hypertensive rabbits. Acta physiol. scand. 1968. 72. 298-309. The baroreceptor activity in the entire left aortic nerve was recorded in 9 normal and 5 hypertensive rabbits. A technique based on rectification and integration of the nerve potentials allowed separate analysis of the mean, systolic and diastolic activities. The nervous activities measured at different diastolic blood pressures showed only small variations during recordings over several hours, and small inter-individual variations. In hypertensive rabbits, the receptors required a higher pressure to start firing than in normal rabbits. The activity was lower at all pressures in hypertensive animals. The difference from normal rabbits increased with increasing pressure, and was most pronounced for the systolic part of the firing. Mechanisms for causing the resetting of baroreceptor activity in hypertension are discussed. It is concluded that a combination of hypertensive wall changes and exhaustion or destruction of some receptors is probably responsible for the resetting.

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Elastizität und Morphologie des Aortenwindkessels beim Bluthochdruck

Cited by 19 publications

References 31 publications

The Distensibility of the Resistance Vessels in Spontaneously Hypertensive Rats (SHR) as Compared with Normotensive Control Rats (NCR)

The Distensibility of the Resistance Vessels in Spontaneously Hypertensive Rats (SHR) as Compared with Normotensive Control Rats (NCR)

Response of the Rat Aortic Media to Hypertension

Aortic Baroreceptor Activity in Normal and Hypertensive Rabbits

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