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Background and Purpose: Intact endothelium plays a pivotal role in post-ischaemic angiogenesis. It is a phenomenon finely tuned by activation and inhibition of several endothelial receptors. The presence of alpha(1)-adrenoceptors on the endothelium suggests that these receptors may participate in regenerative phenomena by regulating the responses of endothelial cells involved in neo-angiogenesis.Experimental Approach: We evaluated the expression of the subtypes of the alpha(1)-adrenoceptor in isolated endothelial cells harvested from Wistar-Kyoto (WKY) rats. We explored the possibility these alpha(1)-adrenoceptors may influence the pro-angiogenic phenotype of endothelial cells in vitro. In vivo, we used a model of hindlimb ischaemia in WKY rats, to assess the effects of alpha(1) adrenoceptor agonist or antagonist on angiogenesis in the ischaemic hindlimb by laser Doppler blood flow measurements, digital angiographies, hindlimb perfusion with dyed beads and histological evaluation.Key Results: In vitro, pharmacological antagonism of alpha(1)-adrenoceptors in endothelial cells from WKY rats by doxazosin enhanced, while stimulation of these adrenoceptors with phenylephrine, inhibited endothelial cell proliferation and DNA synthesis, ERK and retinoblastoma protein (Rb) phosphorylation, cell migration and tubule formation. In vivo, we found increased alpha(1)-adrenoceptor density in the ischaemic hindlimb, compared to non-ischaemic hindlimb, suggesting an enhanced alpha(1)-adrenoceptor tone in the ischaemic tissue. Treatment with doxazosin (0.06 mg kg(-1) day(-1) for 14 days) did not alter systemic blood pressure but enhanced neo-angiogenesis in the ischaemic hindlimb, as measured by all our assays.Conclusions: Our findings support the hypothesis that the alpha(1)-adrenoceptors in endothelial cells provide a negative regulation of angiogenesis. [ABSTRACT FROM AUTHOR]

Background and purpose:Intact endothelium plays a pivotal role in post-ischaemic angiogenesis. It is a phenomenon finely tuned by activation and inhibition of several endothelial receptors. The presence of α1-adrenoceptors on the endothelium suggests that these receptors may participate in regenerative phenomena by regulating the responses of endothelial cells involved in neo-angiogenesis.Experimental approach:We evaluated the expression of the subtypes of the α1-adrenoceptor in isolated endothelial cells harvested from Wistar-Kyoto (WKY) rats. We explored the possibility these α1-adrenoceptors may influence the pro-angiogenic phenotype of endothelial cells in vitro. In vivo, we used a model of hindlimb ischaemia in WKY rats, to assess the effects of α1 adrenoceptor agonist or antagonist on angiogenesis in the ischaemic hindlimb by laser Doppler blood flow measurements, digital angiographies, hindlimb perfusion with dyed beads and histological evaluation.Key results:In vitro, pharmacological antagonism of α1-adrenoceptors in endothelial cells from WKY rats by doxazosin enhanced, while stimulation of these adrenoceptors with phenylephrine, inhibited endothelial cell proliferation and DNA synthesis, ERK and retinoblastoma protein (Rb) phosphorylation, cell migration and tubule formation. In vivo, we found increased α1-adrenoceptor density in the ischaemic hindlimb, compared to non-ischaemic hindlimb, suggesting an enhanced α1-adrenoceptor tone in the ischaemic tissue. Treatment with doxazosin (0.06 mg kg−1 day−1 for 14 days) did not alter systemic blood pressure but enhanced neo-angiogenesis in the ischaemic hindlimb, as measured by all our assays.Conclusions:Our findings support the hypothesis that the α1-adrenoceptors in endothelial cells provide a negative regulation of angiogenesis.British Journal of Pharmacology (2008) 153, 936–946; doi:10.1038/sj.bjp.0707637; published online 17 December 2007 [ABSTRACT FROM AUTHOR]

Background and Purpose: We investigated whether β(2) -adrenoceptor overexpression could promote angiogenesis and improve blood perfusion and left ventricular (LV) remodeling of the failing heart., Experimental Approach: We explored the angiogenic effects of β(2) -adrenoceptor overexpression in a rat model of post-myocardial infarction (MI) heart failure (HF). Cardiac adenoviral-mediated β(2) -adrenoceptor overexpression was obtained via direct intramyocardial injection 4-weeks post-MI. Adenovirus(Ad)-GFP and saline injected rats served as controls. Furthermore, we extended our observation to β(2) -adrenoceptor -/- mice undergoing MI., Key Results: Transgenes were robustly expressed in the LV at 2 weeks post-gene therapy, whereas their expression was minimal at 4-weeks post-gene delivery. In HF rats, cardiac β(2) -adrenoceptor overexpression resulted in enhanced basal and isoprenaline-stimulated cardiac contractility at 2-weeks post-gene delivery. At 4 weeks post-gene transfer, Ad-β(2) -adrenoceptor HF rats showed improved LV remodeling and cardiac function. Importantly, β(2) -adrenoceptor overexpression was associated with a markedly increased capillary and arteriolar length density and enhanced in vivo myocardial blood flow and coronary reserve. At the molecular level, cardiac β(2) -adrenoceptor gene transfer induced the activation of the VEGF/PKB/eNOS pro-angiogenic pathway. In β(2) -adrenoceptor-/- mice, we found a ~25% reduction in cardiac capillary density compared with β(2) -adrenoceptor+/+ mice. The lack of β(2) -adrenoceptors was associated with a higher mortality rate at 30 days and LV dilatation, and a worse global cardiac contractility compared with controls., Conclusions and Implication: β(2) -Adrenoceptors play an important role in the regulation of the angiogenic response in HF. The activation of VEGF/PKB/eNOS pathway seems to be strongly involved in this mechanism., (© 2012 The Authors. British Journal of Pharmacology © 2012 The British Pharmacological Society.)