Structural influences on resistance in the hindlimb vascular bed of the renal hypertensive rabbit.

1. The contribution of arteriolar structural change to hindlimb vascular resistance was examined in the renal wrap hypertensive rabbit. 2. Haemodynamic variables were recorded at rest and after maximal vascular dilation using sodium nitroprusside and peripheral autonomic effector blockade. In the same animals at the end of experiments, morphometric measurements of hindlimb muscle arterioles were made. 3. Mean arterial pressure (MAP) and hindlimb vascular resistance were elevated in hypertensive animals compared with normotensive animals at rest and after maximal dilation. 4. Lumen area and lumen diameter were reduced whereas wall area and wall area to lumen area ratio were increased in hypertensive animals compared with normotensive animals. 5. In the renal wrap model of hypertension, the reduction in lumen area of arterioles, < 200 microns in diameter, is sufficient to explain the increase in haemodynamic resistance.