CARDIOVASCULAR AND ORGAN RESPONSES AND ADAPTATION RESPONSES TO HYPOGRAVITY IN AN EXPERIMENTAL ANIMAL-MODEL

The head-down suspension (i.e antiorthostatic hypokinesia) rat is used to simulate weightlessness. However, little is known about cardiovasc ular and organ adaptation responses which, over a long time, can becom e pathologically significant. The purpose of this study was therefore to evaluate regional changes in the hematology parameters, Endotheline -1 (ET-I) concentration and urinary excretion of N-acetyl-beta-D-gluco saminidase (EC 3.2.1.30) (NAG) in experimental antiorthostatic rat mod el. The indicate significant variations in the plasma ET-I level in ti me, in the superior and inferior cava vessel blood of animals maintain ed for 10 days in hypogravity with respect to controls. These changes do not seem to be due to hemoconcentration. The increase in urinary NA G was observed during the first 24h of experiment, indicating renal st ress, probably due to adverse blood flow variations within the organ. We conclude that the plasma ET-I level changes could be responsible, o verall for the blood flow variations in the kidney and renal stress co uld be the consequence of extended antiorthostatic hypokinesia. The ET -1 behaviour and urinary NAG excretion in rats exposed to antiorthosta tic hypokinetic hydynamia offer possibilities for understanding if the se changes might be reversible or when they become pathological. This could give some relevant information about the effects of prolonged hy pogravity during the space voyage.