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

Spirally 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 sample. Tissues were from unsensitized or ovalbumin-sensitized guinea pigs. Isometric tension was measured and responses to adenosine recorded.

RESULTS

In sensitized tissues, contractile responses to adenosine were evident as contractions of superfused spirals or as rightwards shift of the concentration-response curve compared with non-sensitized immersed spirals. Epithelium removal potentiated relaxation responses in both non-sensitized and sensitized strips indicating release of contractile mediators in both tissues. Dipyridamole potentiated relaxation responses in sensitized tissues with and without epithelium.

CONCLUSION

Sensitization reveals 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.