Abstract
Background and aims: The sphingolipid-derived second messenger ceramide plays an important role in numerous physiological processes. Ceramide generated by neutral sphingomyelinase (nSMase) has been involved in hypoxic pulmonary vasoconstriction (HPV, Cogolludo et al., Cardiovasc Res 2009;82:296-302). HPV shares many similarities with oxygen-induced contraction of the ductus arteriosus (DA). Chicken and mammalian DAs present common mechanisms for oxygen sensing/signaling (Cogolludo et al., Am J Physiol 2009; 297:L619-L630). We aimed to analyse the putative role of ceramide in the response to oxygen in chicken and human DA.Methods: Contractile tension was recorded in DA rings using conventional organ baths (for human) and wire myographs (for 20-d chicken fetuses). Myocytes from these tissues were isolated by enzymatic digestion.Results: Exposure to oxygen (21%) induced contraction in the pulmonary side but relaxation in the aortic side of chicken DA. Similarly, oxygen increased ceramide content measured by immunocytochemistry) only in the pulmonary side of 20-d DA. The nSMase inhibitor GW4869 did not affect endothelin-induced contraction but markedly reduced oxygen-induced contraction in chicken DA. Similar results were obtained with an anticeramide antibody. Moreover, the addition of exogenous C6-ceramide and of Bacillus cereus sphingomyelinase contracted the pulmonary side of chicken DA but had negligible effects in the aortic side. Finally, the normoxic contraction of human DA rings was markedly reduced by GW4869.Conclusions: Our data indicate that nSMase-derived ceramide is a key event in in the signalling cascade of normoxic contraction of chicken and human DA. Supported by Fundación de Investigación Médica Mutua Madrileǹa.
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