[Changes of reactivity of rabbit femoral venous rings after 21 d simulated weightlessness].

Objective: To study the effects of simulated weightlessness on reactivity of leg veins.

Method: Vascular bathing technique was used to measure the contractile responses of rabbit femoral venous rings to Ht, PE and KCl, and the dilatory responses to ACh and SNP after horizontal confinement or head-down tilt confinement for 21 d.

Result: After simulated weightlessness for 21 d, the contractile response of rabbit femoral venous rings to higher concentrations of PE and KCl decreased significantly (P<0.05); the contractile response to Ht also decreased, but not significantly (P>0.05); the dilatory responses to ACh and SNP did not change significantly in both groups.

Conclusion: Contractile response of rabbit femoral vein decreased after simulated weightlessness for 21 d, which might partly explain the occurrence of orthostatic intolerance in men after space flight.