Vascular Distensibility and Remodeling

To characterize the effects of pregnancy and CD4 T cell deficiency on the structure and mechanical behavior of ICAs, we compared passive arterial diameters, wall thickness and distensibility of the vessels from WT and CD4KO virgin and PP mice. The arteries were pressurized at 3 mmHg and superfused for 10 min with PSS containing 20 μM diltiazem and 50 μM papaverine to inhibit vascular contractility and to allow for maximal arterial dilation at each level of intraluminal pressure. Inner (lumen, D_in) and outer (D_out) arterial diameters were defined after stepwise elevation in intraluminal pressure from 3 to 120 mm Hg. Three mmHg is the minimal pressure for an un-stretched vessel that prevented the vessel from collapsing. D_out and D_in were both measured from saved images of pressurized arteries on the monitor screen after stabilization of the diameters at each specific level of pressure (typically, 2–3 min for each pressure step). Arterial wall thickness (t) was calculated as follows: t = (D_out – D_in)/2. Arterial distensibility was defined as an increment in the lumen diameter in response to pressure elevation from 3 to 120 mmHg. The increments in the lumen diameter were expressed as the percentage of an un-stretched vessel diameter at 3 mmHg.