[Effect of two-week tail suspension on the reactivity of rat's cerebral vessels]

Reactivity of the cerebral vessels feeding two different brain regions was studied in rats after the hind limb unloading during two-wk tail-suspension. The basilar and middle cerebral arteries were isolated and perfused with a steady flow of the Krebs solution. Constriction responses to serotonin (10(8)-10(5) M) and high-K+ solution (100 mM) and dilatation responses to the beta-adrenoceptor agonist isoproterenol (10(8)-3 x 10(6) M) were evaluated. Tail suspension had no effect on the reactivity of the middle cerebral artery. The basilar artery reaction to K+ and isoproterenol remained unchanged compare to the control, whereas the reaction to serotonin was augmented significantly. Therefore, regional differences in the cerebral vessels reactivity were observed in rats after two weeks of tail suspension.