[Various hemodynamic mechanisms of the hypertensive reaction in immobilization-induced stress in rabbits and rats]

: The radioactive microsphere technique was used to measure the cardiac output, regional blood flows and resistances in conscious rabbits and rats before and after 30-minute immobilization. Immobilization evoked blood pressure rise in both species. Cardiac output was reduced and total peripheral resistance increased in rabbits. Reverse changes of these parameters were observed in rats. Blood flow was reduced in the liver and the right ventricle in rabbits, and in the testes in rats. In immobilized rats, regional blood flow increased in skeletal muscles, the heart, the adrenals and the liver. These experiments demonstrate different hemodynamic mechanisms of immobilization-induced hypertension in rabbits and rats.