Mechanisms underlying pressor response of subfornical organ to angiotensin II.
In urethane-anesthetized rats, microinjection of angiotensin II (AII) into either the subfornical organ (SFO), nucleus paraventricularis (NPV), or rostral ventrolateral medulla (RVL), respectively, all induced pressor responses, but the heart rate remained unchanged. Preinjection of [Sar1, Thr8]-angiotensin II (ST-AII, an AII antagonist) into bilateral NPV blocked the SFO-pressor response to AII. Bilateral RVL pretreated with ST-All markedly attenuated the pressor response of the SFO or NPV to AII. Hexamethonium or methyl atropine (IV) also reduced the SFO-pressor response. The results show that All can activate the SFO, NPV, and RVL successively, thereby inducing the pressor response; both excitation of sympathetic nerves and inhibition of the cardiac vagus are involved in this response.
Ku
Y H
YH
Department of Physiology, Beijing Medical University, China.
Jia
Y F
YF
Chang
Y Z
YZ
D000804:Angiotensin II / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D000818:Animals; D001286:Atropine Derivatives / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D018738:Hexamethonium / Q000494:pharmacology; D008297:Male; D008526:Medulla Oblongata / Q000187:drug effects; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects; D010646:Phentolamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013356:Subfornical Organ / Q000187:drug effects*; D013564:Sympathetic Nervous System / Q000502:physiology; D014630:Vagus Nerve / Q000502:physiology
D001286:Atropine Derivatives; D000804:Angiotensin II; D018738:Hexamethonium; C006649:methylatropine; D011433:Propranolol; D010646:Phentolamine