Scavenging of vascular endothelial growth factor (VEGF) elevates blood pressure (BP) in patients receiving anti-angiogenic therapy. Similarly, inhibition of circulation VEGF by its soluble receptor fms-like tyrosine kinase-1 (sFlt-1) underlies BP elevation in pre-eclampsia. Both phenotypes are characterized by augmented production of endothelin-1 (ET-1), suggesting a role for ET-1 in anti-angiogenic hypertension. We aimed to assess the effect of VEGF inhibition on ET-1-induced contractility and downstream ET-1 signaling.

Male C57BL/6N mice were treated with either sFlt-1 or vehicle and BP was assessed via tail-cuff. Mean arterial pressure of sFlt-1-treated mice markedly increased compared to vehicle-treated controls (N = 11–12, p<0.05). After sacrifice, carotid and mesenteric arteries were isolated for isometric tension measurements. ET-1-induced contractions were similar in mesenteric arteries of vehicle and sFlt-1-treated mice, but augmented in carotid segments of sFlt-1-treated mice compared to controls (N = 9–10, p<0.05). The increased contraction in carotid segments could be completely abrogated by the cyclooxygenase (COX) inhibitor indomethacin (N = 9–10, p<0.05), indicating heightened prostaglandin-mediated vasoconstriction. This was associated with a shift towards procontractile ET_B signaling in sFlt-1-treated mice, possibly explaining the increased ET-1-induced prostaglandin-mediated vasoconstriction. In line with the ex vivo findings, sFlt-1-induced BP elevation could be prevented in vivo by oral treatment with either a high-dose of the COX inhibitor aspirin (N = 7) or with picotamide (N = 9), a dual thromboxane A₂ synthase inhibitor and receptor antagonist.

VEGF inhibition augments the pressor response to ET-1. The cyclooxygenase-thromboxane signaling route downstream of ET-1 might be a possible target to prevent BP elevation during VEGF inhibition.