AbstractThe organism is exposed to diverse orthostatic stimuli, which can induce several acute and chronic adaptive responses. In this study, we investigated hemodynamic responses elicited by short-term and intermediate-term various orthostatic stimuli, using normotensive and hypertensive rat models. Arterial blood pressure and heart rate were measured by telemetry. Hypertension was induced by NO-synthase blockade. Effect of orthostatic and inverse-orthostatic body positions were examined in 45 head-up (HUT) or head-down tilt (HDT), either for 5min duration repeated 3 times each with a 5-min pause “ R ”, or as sustained tilting for 120min “ S ”. Data are given as mean ± SEM . In normotensives, horizontal control blood pressure was R 115.4 ± 1.4 / S 113.7 ± 1.6 mmHg and heart rate was R 386.4 ± 7.0 / S 377.9 ± 8.8 BPM . HUT changed blood pressure by R < ± 1 ( ns ) / S 4.6 mmHg ( p < 0.05 ) . HDT resulted in augmented blood pressure increase by R 6.2 ( p < 0.05 ) / S 14.4 mmHg ( p < 0.05 ) . In NO-deprived hypertension, horizontal control hemodynamic parameters were R 138.4 ± 2.6 / S 140.3 ± 2.7 mmHg and R 342.1 ± 12.0 / S 346.0 ± 8.3 BPM , respectively. HUT and HDT changed blood pressure further by R < ± 1 ( ns ) / S 5.6 mmHg ( p < 0.05 ) and by R 8.9 ( p < 0.05 ) / S 14.4 mmHg ( p < 0.05 ) , respectively. Heart rate changed only slightly or non-specifically. These data demonstrate that both normotensive and hypertensive conscious rats restricted from longitudinal locomotion respond to sustained orthostasis or inverse-orthostasis related gravitational stimuli with moderate or augmented hypertension, respectively.


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    Title :

    Both sustained orthostasis and inverse-orthostasis may elicit hypertension in conscious rat


    Contributors:

    Published in:

    Acta Astronautica ; 60 , 4-7 ; 415-419


    Publication date :

    2006-01-01


    Size :

    5 pages




    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English