Intracerebroventricular administration of angiotensin II increases heart rate in the conscious trout.
The central effect of angiotensin II on cardiovascular activity has been investigated in conscious trout bearing an intracerebroventricular (i.c.v.) cannula and an intra-arterial catheter. I.c.v. injection of the angiotensin II agonist [Asn1,Val5]AII (6.2-50 pmol) induced a dose-dependent increase in heart rate and arterial blood pressure. Central administration of the angiotensin II antagonist DuP 753 (5 nmol) 30 min before i.c.v. injection of [Asn1,Val5]AII totally prevented the tachycardia and reduced the hypertension induced by the angiotensin II agonist. Intra-arterial injection of arginine-vasotocin (12.5 pmol) caused a bradycardia associated with a marked increase in arterial blood pressure. I.c.v. injection of [Asn1,Val5]AII totally blocked the bradycardia induced by arginine-vasotocin and this effect was prevented by central administration of DuP 753. In contrast, [Asn1,Val5]AII did not affect the increase in blood pressure induced by arginine vasotocin. Suppression of the vagal tone by atropine treatment totally blocked the central effect of [Asn1,Val5]AII. These results show that angiotensin II acts directly on the trout brain to increase blood pressure and heart rate. The effect of angiotensin II is mediated through a receptor related to the mammalian AT1 receptor type.
Le Mevel
J C
JC
Laboratoire de Neurophysiologie, UFR de Médecine, Université de Bretagne Occidentale, Brest, France.
Pamantung
T F
TF
Mabin
D
D
Vaudry
H
H
D000804:Angiotensin II / Q000819:agonists / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000008:administration & dosage / Q000494:pharmacology; D001713:Biphenyl Compounds / Q000008:administration & dosage / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology*; D003243:Consciousness; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects*; D007093:Imidazoles / Q000008:administration & dosage / Q000494:pharmacology*; D007269:Injections, Intra-Arterial; D007276:Injections, Intraventricular; D019808:Losartan; D013777:Tetrazoles / Q000008:administration & dosage / Q000494:pharmacology*; D014337:Trout
D001713:Biphenyl Compounds; D007093:Imidazoles; D013777:Tetrazoles; D000804:Angiotensin II; C031193:angiotensin II, Asp(1)-Val(5)-; D001285:Atropine; D019808:Losartan