[Effect of adaptation to altitude hypoxia on vascular resistance]

The resistance of vessels in the hind limbs was determined under controlled perfusion in rats adapted to hypoxia at 2100 m altitude and in control animals at 200 m above the sea level. It was found that 15 days after the onset of adaptation the resistance of the resistive vessels decreases, after 30 days the degree of this decrease of resistance grows and it becomes statistically significant. The decrease of resistance in the resistive vessels of adapted animals persists after denervation of the extremity and depends on the reduction of the myogenic component of the vascular tonicity. This reduction of the myogenic component of the tonicity is accompanied by a reduction of the pressor reactions to asphyxia and addition of noradrenaline to the perfusate. The obtained data indicate that preliminary adaptation decelerates the development of experimentally induced hypertension.