Experimental production of poststenotic dilatation in the carotid arteries of rabbits.

Arterial dilatation distal to a stenosis has been known as poststenotic dilatation (PSD). This paper describes arterial constriction enough to produce PSD, time course of PSD, structural changes of the dilated segments and influence of hypertension on the development of PSD. These problems were studied in 2 experimental protocols. In protocol I, 87 carotid arteries of 45 rabbits were constricted by silver clip of 0.65 to 2.0 mm in diameter. The arterial diameter was measured at the sites both proximal and distal to the constriction after 3 days to 8 weeks. In protocol II, 22 carotid arteries of 12 rabbits with experimental one-or two-kidney Goldblatt hypertension were constricted and the development of PSD was compared with age matched controls. Remarkable PSD developed in arteries with moderate stenosis of 45 to 60% constriction. The degree of dilatation expressed as ratio of distal to proximal diameter reached about 1.5 at the end of the second week and remained unchanged thereafter. Destruction of the elastic fibers with intimal hyperplasia was observed in the dilated segments even at the early stages of the PSD. Both mild and severe stenosis failed to produce prominent PSD. In protocol II, the PSD averaged 1.18 +/- 0.05 (mean +/- SE) in hypertensive, and 1.32 +/- 0.03 in normotensive animals (p less than 0.05). The result suggests that chronic hypertension decreases the distensibility of the arteries.