[Increase in the structural component of the vascular bed resistance in hypertension and its regulatory sequelae]

The increase in structural component of the resistance in hypertension is due mainly to two factors: a decrease in the arteries lumen and a rarefaction of microcirculatory bed, both factors inducing regulatory changes. The first factor increases constrictor effects in hypertensive animals with high intravascular pressure, and reduces the reactivity in low pressure. The rarefaction of microcirculatory bed occurring in various brain areas in hypertensive rats seems to form local foci of hypoxia in neural tissue and to activate sympathetic nervous system through cerebro-ischemic mechanism.