Reactivity of arterial vessels during antiorthostasis and systemic hypotension.
In experiments on rats, changes in blood pressure and cardiac output in response to antiorthostatic (head-down) tilt 15° and 45° were examined under conditions of decreased arterial tone induced by sodium nitroprusside. The decrease in initial systemic blood pressure to 90 mm Hg attenuated the pressor responses to antiorthostasis, while further drop in blood pressure to 70-60 mm Hg provoked depressor responses in half cases. No blood pressure responses to antiorthostasis were observed when blood pressure dropped to 50 mm Hg. Correlation analysis confirmed the existence of a direct dependence of pressor responses to orthostasis on the initial blood pressure.
Laboratory of Blood Circulation Physiology, I. P. Pavlov Institute of Physiology, Russian Academy of Sciences, St. Petersburg, Russia.
T V
TV
Balueva
I V
IV
Sergeev
D000818:Animals; D001158:Arteries / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology; D018475:Head-Down Tilt / Q000502:physiology*; D007022:Hypotension / Q000503:physiopathology*; D008297:Male; D009599:Nitroprusside / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D014664:Vasodilation / Q000187:drug effects
D009599:Nitroprusside