[Vasoconstrictor responsiveness of rat basilar artery enhanced by simulated weightlessness].
OBJECTIVE
To investigate the effects of simulated weightlessness on contractile responsiveness of the basilar artery.


METHODS
Rats were subjected to tail-suspension for 4-wk to simulate the effect of weightlessness, responses of perfused isolated basilar arterial rings to various vasoactive compounds were examined.


RESULTS
Maximal isometric contractile responses to KCl [ (10~100) mmol/L], arginine vasopressin [AVP, (10(-15)~10(-7) mol/L], or 5-hydroxytryptamine [5-HT, (10(-12) ~ 10(-4) mol/ L] were significantly enhanced in arterial rings isolated from 4-wk tail-suspended as compared with that from simultaneous control rats.


CONCLUSIONS
These results indicate that medium-term simulated weightlessness may result in an enhanced contractile responsiveness in rat basilar artery, and strongly support the hypothesis of cerebrovascular syncope-initiating mechanism.
Zhang
L N
LN
Department of Aerospace Physiology, The Fourth Military Medical University, Xi'an, China.
Ma
J
J
Zhang
L F
LF
D000337:Aerospace Medicine; D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology; D001488:Basilar Artery / Q000187:drug effects*; D019417:Hindlimb Suspension; D007537:Isometric Contraction / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000494:pharmacology; D013575:Syncope / Q000503:physiopathology; D014662:Vasoconstrictor Agents / Q000494:pharmacology*; D018474:Weightlessness Simulation
D014662:Vasoconstrictor Agents; D001127:Arginine Vasopressin; D012701:Serotonin; D011189:Potassium Chloride