Effects of simulated weightlessness on reactivity of pulmonary artery

Objective: To study the effects of simulated weightlessness on reactivity of pulmonary artery.Methods: Rat tail-suspension was used to simulate effects of microgravity.The changes in responses of pulmonary artery to several vasoactive agents were determined by using in vitro vessel rings perfusion technique.Results: Compared with the control group,the contractile responses of pulmonary artery to potassium chloride（KCl,68M）and phenylephrine(PE,10^-9～10^-5M)were markedly diminished after 14day tail-suspension,while the vasoactive responses to acetylcholine(Ach,10^-9～10^-5M)were markedly enhanced.Conclusion: The contractile responsiveness is attenuated and the dilatory responsiveness is enhanced in the pulmonary arteries of rats after simulated weightlessness;impaired contractile responsiveness may contribute to orthostatic intolerance.