Laser-induced thrombus formation and vascular reactivity in the microcirculation of the spontaneously hypertensive rat.

Thrombi formation resulting from laser-induced injury to mesenteric circulation has been studied in spontaneously hypertensive (SH) and normotensive rats. The thrombotic reaction was enhanced in both venules and arterioles of the SH rats. In the arterioles of the hypertensive rats, the vasoconstriction which develops downstream from the thrombus is greatly intensified and the time to form microvascular haemostatic plugs significantly decreased in the arterioles of these animals. These phenomena have been explained on the basis of an increased reactivity of the vascular smooth muscle of the SH rats to vasoconstrictor substances liberated from platelets at the site of injury.