Inward Remodeling Follows Chronic Vasoconstriction in Isolated Resistance Arteries

The hypothesis was tested that chronic vasoconstriction is followed by a structural reduction in lumen diameter, measured at full dilation. An in vitro model of pressurized rat skeletal muscle arterioles was used. During a 3-day experimental period, constriction of active vessels was achieved with fetal calf serum or endothelin-1 (ET-1). Maximal dilation revealed inward remodeling from 179 +/- 6.5 microm lumen diameter on day 0 to 151 +/- 6.3 microm on day 3 at 75 mm Hg in vessels incubated with serum (n = 8). Similarly, ET-1 induced inward remodeling from 182 +/- 5.2 to 164 +/- 3.7 microm (n = 6). When constriction during organoid culture was inhibited with papaverin or verapamil, inward remodeling was fully prevented: 184 +/- 6.3 to 184 +/- 5.8 microm for papaverin (n = 6) and 174 +/- 5.5 to 177 +/- 7.4 microm for verapamil (n = 6). A chronic reduction in diameter without tone was achieved in vessels that were kept at a low pressure (2-5 mm Hg; n = 6). Here, no remodeling was found, thereby ruling out that a chronic reduction in diameter alone is sufficient for inward remodeling. These data show that a persistent active reduction in lumen diameter is followed by inward remodeling of arterioles.