Structural and functional responses of extremity veins to long-term gravitational loading or unloading—lessons from animal systems

Monos, E.; Raffai, Gábor; Dörnyei, Gabriella; Nádasy, György L.; Fehér, Erzsébet

doi:10.1016/j.actaastro.2006.09.027

Cited by 15 publications

(12 citation statements)

References 22 publications

(37 reference statements)

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“…Our previous studies have Acta Physiologica Hungarica 96, 2009 shown for the first time the upward and downward regulation in the function, structure, and innervation state of small-and medium-sized arteries from fore and hind body parts of the same animal subjected to tail-suspended head-down tilt (SUS) over a period of eight weeks and its reversal after the release from SUS (36,38,39). Our results are basically consistent with the findings from other laboratories (8,11,17,20,27,31,35). These findings substantiate in general the hypothesis first raised by Hargens et al (13,33) that microgravity-induced chronic changes in regional vascular transmural pressures due to the removal of hydrostatic pressure gradient may well initiate differential adaptation of vessels in different anatomic regions.…”

supporting

confidence: 91%

“…In some of the previous studies, vascular adaptation to microgravity has been suggested to be a generalized or universal response (5,26). However, there is obviously sufficient evidence in favor of the region-specificity hypothesis (8,11,17,18,20,27,35,36,38,39). Findings of the present study add new evidence in support of the hypothesis by data obtained from large, elastic arteries.…”

Section: Regional Specificity Of Structural Adaptation In Large Artersupporting

confidence: 67%

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Regional specificity of adaptation change in large elastic arteries of simulated microgravity rats

Gao

Bao²,

Xue³

et al. 2009

Acta Physiologica Hungarica

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This study was designed to test the hypothesis that a medium-term simulated microgravity by tailsuspension (SUS) induces hypertrophic and atrophic changes in the common carotid artery and abdominal aorta with their innermost smooth muscle (SM) layers being most profoundly affected. The second purpose was to elucidate whether vascular local renin-angiotensin system (L-RAS) plays an important role in the differential remodeling of the two kinds of large arteries by examining the gene and protein expression of angiotensinogen (A O) and angiotensin II receptor type 1 (AT1R) and their localization in the vessel wall. The results showed that SUS induced an increase in the media thickness of the common carotid artery due to hypertrophy of the four SM layers and a decrease in the total crosssectional area of the nine SM layers of the abdominal aorta without significant change in its media thickness. Irrespective of the nature of remodeling, the most prominent changes were in the innermost layers. Immunohistochemistry, in situ hybridization, Western blot, and real time quantitative PCR analysis revealed that SUS induced an up-and down-regulation in A O and AT1R expression in the common carotid artery and abdominal aorta, respectively. In conclusion, our findings have demonstrated some special features in the structural adaptation of large elastic arteries due to a mediumterm simulated microgravity.

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supporting

confidence: 91%

Section: Regional Specificity Of Structural Adaptation In Large Artersupporting

confidence: 67%

Regional specificity of adaptation change in large elastic arteries of simulated microgravity rats

Gao

Bao²,

Xue³

et al. 2009

Acta Physiologica Hungarica

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“…In the present study, the PT eVect on venous stiVness was similar in the deep brachial vein as in the cutaneous cephalic vein, which might suggest that the training eVects were not predominantly mediated via neural regulation of myogenic tone. However, it cannot be ruled out that such a mechanism contributed to the PT-induced decrements in venous distensibility, since experiments on smaller mammals have shown that prolonged orthostasis-induced elevation of transmural pressure enhances innervation density in vein walls (Zhang 2001;Monos et al 2001Monos et al , 2007. PT-induced increase of myogenic venous tone may also have been brought about by increased local release of vasoactive substances.…”

Section: Discussionmentioning

confidence: 90%

Distensibility in human veins as affected by 5 weeks of repeated elevations of local transmural pressure

Kölegård

Eiken

2011

Eur J Appl Physiol

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The objectives were to investigate the effects of repeated increments in local intravascular pressure (pressure training; PT) on (1) distensibility in two arm veins, and (2) pain in the arm induced by markedly increased intravascular pressure. Elevation of venous distending pressure (DP) in an arm was induced by placing the subject (n = 8) in a pressure chamber with one arm protruding to the outside via a port in the chamber door, and increasing chamber pressure. During 5 weeks, venous DP in one arm was repeatedly (3 × 40 min/week) increased (65-105 mmHg). Pressure-distension relationships were determined in the brachial and cephalic veins by measuring diameter changes by ultrasonography during stepwise increments in DP to 180 mmHg. In the brachial vein, the diameter change in response to an increase in DP from 30 to 180 mmHg (distensibility) was reduced (P < 0.05) in the pressure-trained arm (11%) compared to that in the control arm before (23%) and after (21%) PT. The cephalic vein showed a similar response with a reduced (P < 0.05) distensibility in the pressure-trained arm (20%) compared to that in the control arm before (29%) and after (25%) PT. At any given DP, arm pain was less (P < 0.05) in the pressure-trained arm than in the control arm before and after PT, presumably reflecting the reduced venous distensibility in the pressure-trained arm. The results support the concept that the distensibility of venous walls adapts to meet the demands imposed by the prevailing local transmural pressures.

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“…The dramatic influence of a very small change in hydrostatic pressure gradient has also been well demonstrated with veins. For example, Monos et al (31) have shown that chronic 45°HUT resulted in a doubling of local venous pressure, enhancement of myogenic tone, and sympathetic hyperinnervation in perivascular nerves of the saphenous vein; whereas chronic 45°HDT induced a diminution of myogenic tone in the vein. Finally, the findings of the present study on SUS-induced structural and functional adaptation in cerebral proximal resistance arteries are quite consistent with those reported for genetic and nongenetic hypertensive rats (19,35,36,53,54,62).…”

Section: Region-specific Structural and Functional Adaptations In Smamentioning

confidence: 99%

Contrasting effects of simulated microgravity with and without daily −G_xgravitation on structure and function of cerebral and mesenteric small arteries in rats

Lin

Gao²,

Bai³

et al. 2009

Journal of Applied Physiology

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This study was designed to test the hypothesis that a 28-day tail suspension (SUS) could induce hypertrophy and enhanced myogenic and vasoconstrictor reactivity in middle cerebral arteries (MCAs), whereas atrophy and decreased myogenic and vasoconstrictor responses in mesenteric third-order arterioles (MSAs). Also, in addition to the functional enhancement in MCAs, structural changes in both kinds of arteries and functional decrement in MSAs could all be prevented by the intervention of daily 1-h dorsoventral (-G(x)) gravitation by restoring to standing posture. To test this hypothesis, vessel diameters to pressure alterations and nonreceptor- and receptor-mediated agonists were determined using a pressure arteriograph with a procedure to measure in vivo length and decrease hysteresis of vessel segments and longitudinal middlemost sections of vessels fixed at maximally dilated state were examined using electron microscopy and histomorphometry. Functional studies showed that 28-day tail-suspended, head-down tilt (SUS) resulted in enhanced and decreased myogenic tone and vasoconstrictor responses, respectively, in MCAs and MSAs. Histomorphometric data revealed that SUS-induced hypertrophic changes in MCAs characterized by increases in thickness (T) and cross-sectional area (CSA) of the media and the number of vascular smooth-muscle-cell layers (N(CL)), whereas in MSAs, it induced decreases in medial CSA and T and N(CL). Daily 1-h -G(x) over 28 days can fully prevent these differential structural changes in both kinds of small arteries and the functional decrement in MSAs, but not the augmented myogenic tone and increased vasoreactivity in the MCAs. These findings have revealed special features of small resistance arteries during adaptation to microgravity with and without gravity-based countermeasure.

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Structural and functional responses of extremity veins to long-term gravitational loading or unloading—lessons from animal systems

Cited by 15 publications

References 22 publications

Regional specificity of adaptation change in large elastic arteries of simulated microgravity rats

Regional specificity of adaptation change in large elastic arteries of simulated microgravity rats

Distensibility in human veins as affected by 5 weeks of repeated elevations of local transmural pressure

Contrasting effects of simulated microgravity with and without daily −G_xgravitation on structure and function of cerebral and mesenteric small arteries in rats

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Structural and functional responses of extremity veins to long-term gravitational loading or unloading—lessons from animal systems

Cited by 15 publications

References 22 publications

Regional specificity of adaptation change in large elastic arteries of simulated microgravity rats

Regional specificity of adaptation change in large elastic arteries of simulated microgravity rats

Distensibility in human veins as affected by 5 weeks of repeated elevations of local transmural pressure

Contrasting effects of simulated microgravity with and without daily −Gxgravitation on structure and function of cerebral and mesenteric small arteries in rats

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Contrasting effects of simulated microgravity with and without daily −G_xgravitation on structure and function of cerebral and mesenteric small arteries in rats