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

Gábor Raffai, László Dézsi, Márta Mészáros, Márk Kollai, Emil Monos

Research output: Contribution to journalArticle


The 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{ring operator} head-up (HUT) or head-down tilt (HDT), either for 5 min duration repeated 3 times each with a 5-min pause "R", or as sustained tilting for 120 min "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.

Original languageEnglish
Pages (from-to)415-419
Number of pages5
JournalActa Astronautica
Issue number4-7 SPEC. ISS.
Publication statusPublished - Feb 1 2007


ASJC Scopus subject areas

  • Aerospace Engineering

Cite this