Alterations in Rubidium-86 Extraction in Normal Mouse Tissues after Irradiation: An Estimate of Long-Term Blood Flow Changes in Kidney, Lung, Liver, Skin and Muscle

The arterial wall undergoes substantial remodeling whenever the local blood flow changes for more than a few days [1]. An increase in flow causes an increase in inner radius, which occurs in two phases and tends to restore the baseline levels of intimal shear stress [2]. Firstly, an acute dilation of the artery occurs due to relaxation of vascular smooth muscle (VSM) cells [3]. Secondly, a long-term media reconstruction takes place, during which VSM cells migrate and proliferate circumferentially causing an increase in undeformed lumen. Moreover, arterial wall thickens to restore the altered wall stress [4].

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Arterial properties of the carotid and femoral artery in endurance-trained and paraplegic subjects

Journal of Applied Physiology ◽

10.1152/jappl.2000.89.5.1956 ◽

2000 ◽

Vol 89 (5) ◽

pp. 1956-1963 ◽

Cited By ~ 91

Author(s):

Arno Schmidt-Trucksäss ◽

Andreas Schmid ◽

Christian Brunner ◽

Nicole Scherer ◽

Guido Zäch ◽

...

Keyword(s):

Blood Flow ◽

Shear Rate ◽

Femoral Artery ◽

Arterial Wall ◽

Activity Level ◽

Functional Adaptation ◽

Local Blood Flow ◽

Flow Changes ◽

The Impact

In humans, the relationships of blood flow changes to structure, function, and shear rate of conducting arteries have not been thoroughly examined. Therefore, the purpose of this study was to investigate these parameters of the elastic-type, common carotid artery (CCA) and the muscular-type, common femoral artery (CFA) in long-term highly active and extremely inactive individuals, assuming that the impact of activity-induced blood flow changes on conduit arteries, if any, should be seen in these subjects. We examined 21 highly endurance-trained athletes (A), 10 paraplegic subjects (P), and 20 sedentary subjects (S) by means of noninvasive ultrasound. As a result, the CFA diameter and compliance were highest in A (9.7 ± 0.81 mm; 1.84 ± 0.54 mm2/kPa) and lowest in P (5.9 ± 0.7 mm; 0.54 ± 0.27 mm2/kPa) compared with S (8.3 ± 1.0 mm; 0.92 ± 0.48 mm2/kPa) with P < 0.01 among the groups. Both parameters correlated with each other ( r = 0.62; P < 0.01). Compared with A (378 ± 84 s−1; 37 ± 15 s−1) and S (356 ± 113 s−1; 36 ± 20 s−1), the peak and mean shear rates of the CFA were almost or more than doubled in P (588 ± 120 s−1; 89 ± 26 s−1). In the CCA, only the compliance and peak shear rate showed significant differences among the groups (A: 1.28 ± 0.47 mm2/kPa, 660 ± 138 s−1; S: 1.04 ± 0.27 mm2/kPa, 588 ± 109 s−1; P: 0.65 ± 0.22 mm2/kPa, 490 ± 149 s−1; P < 0.05). In conclusion, the results suggest a structural and functional adaptation in the CFA and a predominantly functional adaptation of the arterial wall properties to differences in the physical activity level and associated exercise-induced blood flow changes in the CCA. The results for humans confirm those from animal experiments. Similar shear rate values of S and P in the CFA support the hypothesis of constant shear stress regulation due to local blood flow changes in humans. On the other hand, the increased shear rate in the CFA in P indicates an at least partially nonphysiological response of the arterial wall in long-term chronic sympathectomy due to a change in local blood flow.

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