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

In humans, the relationships of blood flow changes to structure, function, and shear rate of conducting arteries have not been thoroughly examined. Th erefore, the purpose of this study was to investigate these parameters of t he elastic-type, common carotid artery (CCA) and the muscular-type, common femoral artery (CFA) in long-term highly active and extremely inactive indi viduals, 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 mm(2)/kPa) and lowest in P (5.9 +/- 0.7 mm; 0.54 +/- 0.27 mm(2)/kPa) co mpared with S (8.3 +/- 1.0 mm; 0.92 +/- 0.48 mm(2)/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 almos t or more than doubled in P (588 +/- 120 s(-1); 89 +/- 26 s(-1)). In the CC A, only the compliance and peak shear rate showed significant differences a mong the groups (A: 1.28 +/- 0.47 mm(2)/kPa, 660 +/- 138 s(-1): S: 1.04 +/- 0.27 mm(2)/kPa, 588 +/- 109 s(-1); P: 0.65 +/- 0.22 mm(2)/kPa, 490 +/- 149 s(-1): P < 0.05). In conclusion, the results suggest a structural and func tional adaptation in the CFA and a predominantly functional adaptation of t he arterial wall properties to differences ill 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 regu lation due to local blood flow changes in humans. On the other hand, the in creased shear rate in the CFA in P indicates an at least partially nonphysi ological response of the arterial wall in long-term chronic sympathectomy d ue to a change in local blood flow.