Role of angiotensin II receptor subtypes in porcine basilar artery: Functional, radioligand binding, and cell culture studies

Abstract

We aimed to clarify responsiveness to angiotensin (Ang) II in the porcine basilar artery and the role of Ang II receptor subtypes by functional, radioligand binding, and cell culture studies. Ang II induced more potent contractions in the proximal part than in the distal part of isolated porcine basilar arteries. The contraction induced by Ang II was inhibited by the Ang II type 1 (AT 1 ) receptor antagonist losartan, but the Ang II type 2 (AT 2 ) receptor antagonist PD123319 enhanced it. After removal of the endothelium, the effect of losartan remained but the effect of PD123319 was abolished. The specific binding site of [ 3 H]Ang II on the smooth muscle membrane was inhibited by losartan, but not by PD123319. Stimulation of angiotensin II increased nitric oxide (NO) production in cultured basilar arterial endothelial cells. This production was inhibited by PD123319 and the NO synthase inhibitor L-N G -nitroarginine. These results suggest that the contraction induced by Ang II might be mediated via the activation of AT 1 receptors on the basilar arterial smooth muscle cells and be modulated via the activation of AT 2 receptors on the endothelial cells, followed by NO production.

Vasomotor effects of 5-hydroxytryptamine, histamine, angiotensin II, acetylcholine, noradrenaline, and bradykinin on the cerebral artery of bottlenose dolphin (<i>Tursiops truncatus</i>)

“…Ang II and ACh did not induce any vasomotor action in the dolphin cerebral artery. In contrast, Ang II induced a very weak contraction in the porcine cerebral artery, with a variation in proximal to distal part responses and a variation in repeated application responses [ 24 ]. ACh did not induce any vasomotor action in the porcine cerebral artery either (unpublished data).…”

“…Although there has been extensive research on the vascular reactivity of different terrestrial and amphibious animals, information regarding vascular reactivity in aquatic animals is limited. We have previously characterized the cerebral artery responsiveness to intrinsic vasoactive substances in pig [ 16 , 17 , 18 , 21 , 22 , 23 , 24 ], and have extensively researched pig cerebral artery function [ 10 , 21 , 22 , 24 ]. In addition, it has been demonstrated a close phylogenetic relationship between pig and dolphin [ 5 , 27 ].…”

A Systematic Review of the Complex Effects of Cannabinoids on Cerebral and Peripheral Circulation in Animal Models

“…This finding again stresses the importance of the choice of the most adequate model species. The porcine basilar artery has repeatedly served as a model for vascular tone studies (Miyamoto et al, 1998 , 2006 ).…”