Eugenol dilates mesenteric arteries and reduces systemic BP by activating endothelial cell TRPV4 channels

Abstract

BACKGROUND AND PURPOSEEugenol, a vanilloid molecule found in some dietary plants, relaxes vasculature in part via an endothelium-dependent process; however, the mechanisms involved are unclear. Here, we investigated the endothelial cell-mediated mechanism by which eugenol modulates rat mesenteric artery contractility and systemic BP. EXPERIMENTAL APPROACHThe isometric tension of rat mesenteric arteries (size 200-300 μm) was measured using wire myography; non-selective cation currents (ICat) were recorded in endothelial cells using patch clamp electrophysiology. Mean arterial pressure (MAP) and heart rate (HR) were determined in anaesthetized rats. KEY RESULTSEugenol relaxed endothelium-intact arteries in a concentration-dependent manner and this effect was attenuated by endothelium denudation. L-NAME, a NOS inhibitor, a combination of TRAM-34 and apamin, selective blockers of intermediate and small conductance Ca 2+ -activated K + channels, respectively, and HC-067047, a TRPV4 channel inhibitor, but not indomethacin, a COX inhibitor, reduced eugenol-induced relaxation in endothelium-intact arteries. Eugenol activated HC-067047-sensitive ICat in mesenteric artery endothelial cells. Short interfering RNA (siRNA)-mediated TRPV4 knockdown abolished eugenol-induced ICat activation. An i.v. injection of eugenol caused an immediate, transient reduction in both MAP and HR, which was followed by prolonged, sustained hypotension in anaesthetized rats. This sustained hypotension was blocked by HC-067047. CONCLUSIONS AND IMPLICATIONSEugenol activates TRPV4 channels in mesenteric artery endothelial cells, leading to vasorelaxation, and reduces systemic BP in vivo. Eugenol may be therapeutically useful as an antihypertensive agent and is a viable molecular candidate from which to develop second-generation TRPV4 channel activators that reduce BP. AbbreviationsEDHF, endothelium-derived hyperpolarizing factor; ICat, non-selective cation currents; IKCa, intermediate conductance calcium-activated potassium channel; MAP, mean arterial pressure; PGI2, prostacyclin; siRNA, short interfering RNA; SKCa, small conductance calcium-activated potassium channel; TRP, transient receptor potential BJP British Journal of Pharmacology

Downregulation of endothelial transient receptor potential vanilloid type 4 channel underlines impaired endothelial nitric oxide-mediated relaxation in the mesenteric arteries of hypertensive rats

“…To explain the observed significant dependence of 4αPDD-induced relaxation on stimulation of endothelial TRPV4 channels, immunohistochemical analysis was employed and it revealed that TRPV4 channels are mainly expressed on the endothelium of mesenteric arteries in both WKY and SHR, and in agreement with previous studies on mouse mesenteric and aortic arteries (Zhang et al 2009, Mendoza et al 2010, and rat mesenteric, pulmonary and carotid arteries (Loot et al 2008, Willette et al 2008, Sukumaran et al 2013, Peixoto-Neves et al 2015. Furthermore, the immunofluorescent signal for TRPV4 protein that was seen in the endothelial cells of wild-type mesenteric and carotid arteries was not seen in those of TRPV4 -/mice (Hartmannsgruber et al 2007, Mendoza et al 2010).…”

Transient receptor potential vanilloid‐4 channels are involved in diminished myogenic tone in brain parenchymal arterioles in response to chronic hypoperfusion in mice

“…An alternative pathway is that increased intracellular calcium in vascular endothelial cells activates NOS and subsequent vasodilation through NO‐related mechanism . This idea is based on a previous study showing that L‐NAME, an NOS inhibitor, blocked TRPV4‐mediated vasodilation in mesenteric arteries . However, this mechanism is unlikely because chronic hypoperfusion did not affect vasoconstriction of PAs to NOS inhibitor L‐NNA, suggesting NO production was not increased after UCCAo.…”

Endothelial dysfunction and vascular disease - a 30th anniversary update

“…, see section ), also cause relaxations which are partly endothelium‐dependent (with both NO and EDH contributing) and are due to the opening of endothelial TRPV4 channels (Peixoto‐Neves et al . ), while their endothelium‐independent vasodilator properties result from inhibition of L‐type Ca 2+ channels in vascular smooth muscle (Raffai et al . ).…”