Sildenafil-Induced Revascularization of Rat Hindlimb Involves Arteriogenesis through PI3K/AKT and eNOS Activation

Area of Science:

• Vascular Biology
• Pharmacology
• Ischemia Research

Background:

• Hypoxia and inflammation are key factors in revascularization after ischemia.
• Sildenafil's mechanism for inducing revascularization, despite inhibiting phosphodiesterase-5 and increasing cGMP, is not fully understood.

Purpose of the Study:

• To investigate the effects of sildenafil on post-ischemic revascularization.
• To elucidate the molecular pathways involved in sildenafil-mediated revascularization.

Main Methods:

• Rats underwent femoral artery ligation, with some receiving sildenafil (25 mg/kg/day).
• Vascular density, blood flow, and arteriolar density were assessed.
• Expression of HIF-1α, VEGF, PI3-kinase, Akt, and eNOS was analyzed.
• Effects of anti-VEGF antibodies were evaluated.

Main Results:

• Sildenafil significantly increased vascular density and blood flow in ischemic limbs compared to controls.
• Sildenafil treatment did not alter VEGF or HIF-1α expression, suggesting angiogenesis independence.
• PI3-kinase, Akt, and eNOS activation was observed with sildenafil, linked to outward arterial remodeling (arteriogenesis).

Conclusions:

• Sildenafil promotes tissue blood flow and arteriogenesis post-ischemia.
• These effects are independent of the VEGF pathway.
• Sildenafil's action involves the PI3-kinase/Akt/eNOS signaling cascade.