Dilatation of cerebral parenchymal vessels mediated by angiotensin type 1 receptor in cats

Masaki Takao; Masahiro Kobari; Norio Tanahashi; Minoru Tomita; Masako Yokoyama; Yutaka Tomita; Manabu Otomo; Koji Inoue; Yasuo Fukuuchi

doi:10.1016/s0304-3940(01)02493-4

Dilatation of cerebral parenchymal vessels mediated by angiotensin type 1 receptor in cats

Neurosci Lett. 2002 Jan 25;318(2):108-12. doi: 10.1016/s0304-3940(01)02493-4.

Authors

Masaki Takao¹, Masahiro Kobari, Norio Tanahashi, Minoru Tomita, Masako Yokoyama, Yutaka Tomita, Manabu Otomo, Koji Inoue, Yasuo Fukuuchi

Affiliation

¹ Department of Neurology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan. [email protected]

PMID: 11796197
DOI: 10.1016/s0304-3940(01)02493-4

Abstract

We report the effects of angiotensin II (ANG-II), as well as angiotensin II type 1 (AT1) and type 2 receptor antagonists (CV-11974 and PD-123319, respectively) on the cerebral parenchymal microvessels in cats using the photoelectric method. ANG-II continuously and dose-dependently increased the cerebral blood volume (CBV) for 15 min. Maximum CBV increases were +0.36+or-0.11 vol% for 0.01 nmol/kg (P<0.05), +0.51+or-0.24 vol% for 0.1 nmol/kg (P<0.05), +1.87+or-0.55 vol% for 1 nmol/kg (P<0.05), and +2.14+or-0.77 vol% for 10 nmol/kg (P<0.05). Systemic arterial blood pressure increased at only 1 min following ANG-II infusion (1 and 10 nmol/kg). CV-11974 and PD-123319 per se did not change the resting CBV. CV-11974 completely inhibited the vasodilatory action of ANG-II, however, PD-123319 did not block it. We conclude that ANG-II directly dilates the parenchymal vessels through the AT1 receptor without increasing systemic blood pressure, and that intrinsic ANG-II may not be associated with maintenance of resting vascular tone.

MeSH terms

Angiotensin II / metabolism*
Angiotensin II / pharmacology
Angiotensin Receptor Antagonists
Animals
Antihypertensive Agents / pharmacology
Benzimidazoles / pharmacology
Biphenyl Compounds
Blood Pressure / drug effects
Cats
Cerebral Arteries / drug effects
Cerebral Arteries / metabolism*
Cerebral Cortex / blood supply*
Cerebral Cortex / drug effects
Cerebral Cortex / metabolism
Cerebrovascular Circulation / drug effects
Cerebrovascular Circulation / physiology*
Dose-Response Relationship, Drug
Female
Imidazoles / pharmacology
Male
Microcirculation / drug effects
Microcirculation / metabolism*
Pyridines / pharmacology
Receptor, Angiotensin, Type 1
Receptor, Angiotensin, Type 2
Receptors, Angiotensin / agonists
Receptors, Angiotensin / metabolism*
Tetrazoles / pharmacology
Vasodilation / drug effects
Vasodilation / physiology*

Substances

Angiotensin Receptor Antagonists
Antihypertensive Agents
Benzimidazoles
Biphenyl Compounds
Imidazoles
Pyridines
Receptor, Angiotensin, Type 1
Receptor, Angiotensin, Type 2
Receptors, Angiotensin
Tetrazoles
Angiotensin II
PD 123319
candesartan