Influences of prostanoids and nitric oxide on post-suspension hypotension in female Sprague-Dawley rats.
Impairment in cardiovascular functions sometimes manifested in astronauts during standing postflight, may be related to the diminished autonomic function and/or excessive production of endothelium-dependent relaxing factors. In the present study, using the 30 degrees head-down tilt (HDT) model, we compared the cardiovascular and biochemical effects of 7 days of suspension and a subsequent 6-h post-suspension period between suspended and non-suspended conscious female Sprague-Dawley rats. Mean arterial pressure (MAP) and heart rate were measured prior to suspension (basal), daily thereafter, and every 2h post-suspension. Following 7 days of suspension, MAP was not different from their basal values, however, upon release from suspension, MAP was significantly reduced compared to the non-suspended rats. Nitric oxide levels were elevated while thromboxane A(2) levels declined significantly in both plasma and tissue samples following post-suspension. The levels of prostacyclin following post-suspension remained unaltered in plasma and aortic rings but was significantly elevated in carotid arterial rings. Therefore, the post-suspension reduction in mean arterial pressure is due mostly to overproduction of nitric oxide and to a lesser extent prostacyclin.
Eatman
D
D
Departments of Pharmacology/Toxicology, Morehouse School of Medicine, 720 Westview Drive, S.W., Atlanta, GA 30310-1495, USA.
Listhrop
R A
RA
Beasley
A S
AS
Socci
R R
RR
Abukhalaf
I
I
Bayorh
M A
MA
D015121:6-Ketoprostaglandin F1 alpha / Q000378:metabolism; D000818:Animals; D001013:Aorta, Thoracic / Q000378:metabolism; D001794:Blood Pressure; D002339:Carotid Arteries / Q000378:metabolism; D011464:Epoprostenol / Q000097:blood; D005260:Female; D006339:Heart Rate; D006801:Humans; D007022:Hypotension / Q000209:etiology* / Q000503:physiopathology*; D066298:In Vitro Techniques; D009569:Nitric Oxide / Q000097:blood* / Q000378:metabolism; D011453:Prostaglandins / Q000097:blood* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018561:Space Simulation; D013928:Thromboxane A2 / Q000097:blood; D013929:Thromboxane B2 / Q000378:metabolism; D014893:Weightlessness / Q000009:adverse effects; D018474:Weightlessness Simulation / Q000009:adverse effects*
D011453:Prostaglandins; D009569:Nitric Oxide; D013929:Thromboxane B2; D013928:Thromboxane A2; D015121:6-Ketoprostaglandin F1 alpha; D011464:Epoprostenol