Function of connexin 43 and RhoA/LIMK2/Cofilin signaling pathway in transient changes of contraction and dilation of human umbilical arterial smooth muscle cells

Background: Post-induction hypotension, a common complication after propofol-based induction regimen, is a life-threatening challenge for anesthesiologists especially when unexpected pre-induction hypertension characterized by angiotensin release and increased vascular tone was presented by the same patient. Gap junctions (GJs) composed of connexin 43 (Cx43) have been considered a key factor in regulating vascular contraction and dilation. We aimed to explore the role of Cx43-GJs during peri-induction blood pressure fluctuation and elucidate the underlying mechanisms.

Methods: Human umbilical arterial smooth muscle cells (HUASMCs) were pretreated by short-term Angiotensin Ⅱ (Ang Ⅱ) with or without subsequent propofol treatment to simulate transient contraction and dilation of vascular smooth muscle cells during anesthesia induction. F-actin polymerization, a classic indicator of HUASMCs constriction, was determined by F-actin staining assay. Both the function and expression of Cx43-GJs during transient contraction and dilation of HUASMCs, and their potential regulation of downstream CA²⁺/RhoA/LIMK2/Cofilin signaling pathway were explored via different targeting inhibitors and siRNAs.

Results: Ang Ⅱ pretreatment significantly induced F-actin polymerization that indicate cell contraction, accompanied by enhanced GJs function on HUASMCs. With the inhibition of Cx43 GJs by the specific inhibitor, Gap26, and Cx43-siRNA, Ang Ⅱ-induced F-actin polymerization was reversed accompanied with the decrease of intracellular CA²⁺ mobility and the RhoA/LIMK2/Cofilin signaling pathway activity. We also noticed that propofol application could inhibit GJs function, the same as Gap26. Simultaneously, intracellular CA²⁺ mobility and RhoA/LIMK2/Cofilin signaling pathway activity on HUASMCs were both downregulated, finally resulting in downstream reduction of F-actin polymerization.

Conclusion: The function of Cx43-GJs lies in the center of Ang Ⅱ-induced contraction of HUASMCs, which potentially regulates intracellular CA²⁺ mobility as well as RhoA/LIMK2/Cofilin signaling pathway activity. Propofol can reverse this effect induced by Ang Ⅱ through suppressing the function of Cx43-GJs.

Angiotensin Ⅱ; Connexin 43; Gap junction; Propofol.