It is well-known that the thickness of the arterial wall increases in response to hypertension. This is considered to be a homeostatic response of vascular smooth muscle cells to maintain circumferential stress within the wall at a constant level in a physiological condition. However, such homeostatic response does not appear in the axial direction. In fact, axial stress is not maintained at a constant level and instead decreases in response to hypertension. To investigate the cause of this, we examined the deformation of smooth muscle cell nuclei within the vessel wall during tensile loading. As a result, nuclear deformation in response to circumferential stretch was about 25% of the tissue deformation, whereas it was only about 5% in response to axial stretch. Nuclear deformation has been suggested to enhance protein synthesis. Therefore, the small degree of nuclear deformation in the axial direction may be a reason why axial stress is not maintained in response to hypertension.
MATSUMOTO et al. (Wed,) studied this question.