BACKGROUND - Indomethacin treatment for patent ductus arteriosus (PDA) is associated with acute kidney injury (AKI). Fenoldopam, a dopamine (DA) DA-like receptor agonist dilates the renal vasculature and may preserve renal function during indomethacin treatment. However, limited information exists on DA receptor-mediated signaling in the ductus and fenoldopam may prevent ductus closure given its vasodilatory nature.
METHODS - DA receptor expression in CD-1 mouse vessels was analyzed by qPCR and immunohistochemistry. Concentration-response curves were established using pressure myography. Pretreatment with SCH23390 (DA-like receptor antagonist), phentolamine (α -adrenergic receptor antagonist) or indomethacin addressed mechanisms for DA-induced changes. Fenoldopam's effects on postnatal ductus closure were evaluated in vivo.
RESULTS - DA receptors were expressed equally in ductus and aorta. High-dose DA induced modest vasoconstriction under newborn O conditions. Phentolamine inhibited DA-induced constriction, while SCH23390 augmented constriction, consistent with a vasodilatory role for DA receptors. Despite this, fenoldopam had little effect on ductus tone nor indomethacin- or O-induced constriction and did not impair postnatal closure in vivo.
CONCLUSION(S) - DA receptors are present in the ductus but have limited physiologic effects. DA-induced ductus vasoconstriction is mediated via α-adrenergic pathways. The absence of DA-mediated impairment of ductus closure supports the study of potential role for fenoldopam during PDA treatment.