Vascular endothelial growth factor vascular permeability factor produces nitric oxide-dependent hypotension - Evidence for a maintenance role in quiescent adult endothelium

In vitro studies suggest that vascular endothelial growth factor/vascular permeability factor (VEGF/VPF) may stimulate release of nitric oxide (NO) from endothelial cells. To investigate the hemodynamic consequences of recombinant VEGF/VPF administered in vivo, recombinant human VEGF/VPF was administered as a bolus dose of 500 mu g to anesthetized (n=6) or conscious (n=5) New Zealand White rabbits, as well as anesthetized rabbits with diet-induced hypercholesterolemia (HC; n=7). Anesthetized Yorkshire farm pigs (no specific dietary pretreatment) were studied before and after receiving 500 mu g intravenous (IV; n=5) or intracoronary (IC; n=5) VEGF/VPF. In anesthetized, normal rabbits, mean arterial pressure (MAP) fell by 20.5+/-1.4% (P<.05 versus baseline) within 3 minutes after IV VEGF/VPF. Pretreatment with N-omega-nitro-L-arginine caused a significant inhibition of VEGF/VPF-induced hypotension. In conscious, normal rabbits, VEGF/VPF produced a consistent though lesser reduction in MAP. The fall in MAP induced by VEGF/VPF in anesthetized, HC rabbits (21.5+/-2.5% from baseline) was no different from that observed in normal anesthetized rabbits. In pigs, both TV and IC administration of VEGF/VPF produced a prompt reduction in MAP. Heart rate increased, while cardiac output, stroke volume, left atrial pressure, and total peripheral resistance all declined to a similar, statistically significant degree in both IV and IC groups. Epicardial echocardiography disclosed neither global nor segmental wall motion abnormalities in response to VEGF/VPF. We conclude that (1) VEGF/VPF-stimulated release of NO, previously suggested in vitro, occurs in vivo; (2) this finding suggests that functional VEGF/VPF receptors are present on quiescent adult endothelium, consistent with a maintenance function for VEGF/VPF, which may include regulation of NO; and (3) the preserved response of HC rabbits suggests that endothelial cell receptors for VEGF/VPF are spared in the setting of hypercholesterolemia.