The effects of short range and long range pressure changes on the geometry and biomechanics of a superficial leg vein were systematically studied. In vivo and in vitro pressure-diameter curves were taken on the rat saphenous vein of control animals and of animals kept in special head-up tilting cages for two weeks. Pressure-induced acute changes in diameter were not extensive. E.g. raising in vivo venous pressure from 7.9±1.1 to 30.3±1.5 mmHg increased outer diameter only by 5.1%, lowering it to 0.8±0.2 mmHg decreased the latter only by 8.8%. On the other hand, 12 μM norepinephrine and 40 nM endothelin-I reduced in vivo outer diameter at physiological pressures by 18.4 and 64.2%, respectively. Two weeks of elevated leg venous pressure by tilt position increased the diameter of the saphenous vein (e.g. inner radii at 10 mmHg, in vitro, 305±17 and 356±17 μm, p<0.05). Wall stress and elastic modulus were also increased. These studies demonstrate that venous diameter in vivo is rigidly set by the length of the contractile elements (smooth muscle), elastic changes have only secondary importance. Two weeks elevation of intraluminal pressure induces biomechanical changes resembling those of the early phase of the development of varicosities in humans.
|Publication status||Published - Mar 20 1998|
ASJC Scopus subject areas
- Molecular Biology