Responses to adenosine of isolated transverse or spiral strips of sensitized guinea pig trachea: role of epithelium

AIM: To determine the role of the epithelium in the responses to adenosine of isolated trachea from ovalbumin-sensitized guinea pigs. METHODS: Spirall y cut tracheal preparations were superfused or immersed in organ baths and transversely cut strips were immersed. Epithelium was removed mechanically from some strips and confirmed by histological examination of a random samp le. Tissues were from unsensitized or ovalbumin-sensitized guinea pigs. Iso metric tension was measured and responses to adenosine recorded. RESULTS: I n sensitized tissues, contractile responses to adenosine were evident as co ntractions of superfused spirals or as rightwards shift of the concentratio n-response curve compared with non-sensitized immersed spirals. Epithelium removal potentiated relaxation responses in both nonsensitized and sensitiz ed strips indicating release of contractile mediators in both tissues. Dipy ridamole potentiated relaxation responses in sensitized tissues with and wi thout epithelium. CONCLUSION: Sensitization re veals a contractile response to adenosine. The epithelium is not involved in this contractile response nor is it the major site of uptake of adenosine in both sensitized and non- sensitized tissues.