High flow conditions increase connexin43 expression in a rat arteriovenous and angioinductive loop model

Area of Science:

• Cardiovascular Biology
• Molecular Medicine
• Vascular Biology

Background:

• Gap junctions, formed by connexins (Cx), are crucial for vascular growth and adapt to hemodynamic changes.
• Four connexin subtypes (Cx37, Cx40, Cx43, Cx45) are present in the cardiovascular system.
• The impact of high flow on specific connexin expression in vivo remains to be fully elucidated.

Purpose of the Study:

• To investigate the hypothesis that high flow conditions modulate vascular connexin expression in vivo.
• To examine the effect of enhanced blood flow and pulsatility on connexin expression in a rat arteriovenous loop model.

Main Methods:

• Utilized a rat arteriovenous (AV) loop model created by interposing a femoral vein graft.
• Analyzed neovascularization, blood flow (∼4.5-fold increase), and pulsatility in the grafted vessel.
• Assessed protein and mRNA expression of connexins (Cx37, Cx40, Cx43) via immunostaining and RT-PCR.

Main Results:

• Significant neovascularization was observed originating from the venous graft.
• Cx43 protein and mRNA expression were markedly enhanced in the graft endothelium under high flow conditions.
• Cx37 mRNA expression remained unchanged, while Cx40 mRNA expression was reduced.

Conclusions:

• Enhanced blood flow and oscillations in an AV loop model induce selective upregulation of Cx43 expression in the vein.
• This Cx43 upregulation is likely transcriptionally driven and may contribute to neovascularization observed in the model.
• The AV loop serves as a reliable model for studying the association between high flow and Cx43 expression in vivo.