Elastic properties of small intramural coronary arteries of the rat were determined in vitro in order to characterize their mechanical behavior. End branches of the left descendent coronary artery were prepared, cannulated and immersed in a tissue bath. Intraluminal pressure was changed between 0-150 mmHg at a rate of 1 mmHg/sec. Outer diameter of the segments was continuously measured by in vitro microangiometry. Pressure-diameter plots were recorded in spontaneous contraction, in PGF2α (7.5 × 10-6 M) induced contraction, and in relaxed segments (2.8 × 10-4 M papaverine). At 50 mmHg pressure the segments had an outer radius of 172 ± 17 μm, a wall thickness of 34 ± 12 μm, a spontaneous tone of 10.6 ± 3.4 % and a PGF2α tone of 17.5 ± 4.0 % of the relaxed diameter. Elastic modulus at 50 mmHg was 6.8 ± 2.6 × 10-6 dyn/cm2, distensibility 9.5 ± 4.0 × 10-6 cm2/dyn. Elastic modulus and distensibility decreased with increasing pressure: the transition between the more distensible and less distensible parts of the pressure radius curve was below the level of in vivo arterial pressures. This study provides novel information on large deformation biomechanics of intramural small coronary arteries. In addition, it shows that these vessels exhibit significant spontaneous myogenic tone and substantial reactivity when stimulated with agonists.
|Publication status||Published - Dec 1 1997|
ASJC Scopus subject areas
- Molecular Biology