Connexin mimetic peptide 40,37GAP26, a biologically active peptide, matches the GAP26 domain of the extracellular loop of major vascular connexins Cx37 and Cx40, referred to as 37,40Gap26 based on Cx homology. It has been utilized to examine gap junctions' involvement in propagating endothelial hyperpolarizations induced by cyclopiazonic acid (CPA) in the rodent iliac artery wall. Abundant gap junction plaques comprising Cx37 and Cx40 are present in the endothelium, and the peptide exerts inhibitory actions on subintimal hyperpolarization.