Mechanical responses to COREXIT® EC9500A in rat trachea in vitro

Abstract

Oil dispersant COREXIT® EC9500A (CE) was used to reduce the environmental impact of the Deepwater Horizon oil spill in 2010. Little is known of the pulmonary effects of CE on airway smooth muscle and nerves. We investigated in vitro the effects of CE on rat tracheal preparations. In tracheal strips, CE (0.001 %v/v) elicited relaxation. Contraction occurred at higher concentrations (0.003–0.1 %v/v; EC50 0.0031 %v/v). CE (>0.1 %v/v) elicited relaxation of methacholine (MCh; 3×10−5 M)‐contracted strips (EC50 0.39 %v/v). CE (0.003 %v/v) had no effect on MCh‐induced tone but inhibited neurogenic contractile responses of strips to electrical field stimulation (10 Hz). In the isolated, perfused trachea preparation (IPT), in which agents may be applied separately to the mucosal or serosal surface, CE (0.3–10 %v/v) administered to the mucosal bath resulted in contraction. In MCh‐contracted perfused tracheas, mucosal CE (0.1–10 %v/v) elicited contraction followed by relaxation. Thus, CE was less potent in the IPT compared to strips. CE produced a progressive precipitate at >0.1 %v/v. Our results indicate that CE contracts airway smooth muscle and inhibits excitatory neurotransmission. Relaxation at high CE concentrations cannot be distinguished from precipitate formation or osmotic effects.