Elevated circulating adenosine level potentiates antigen-induced immediate bronchospasm and bronchoconstrictor mediator release in sensitized guinea pigs.
BACKGROUND
Adenosine causes bronchoconstriction in asthmatic patients, and it is also accepted that adenosine influences histamine release from activated human mast cells and basophils in vitro.


OBJECTIVE
In this study we tested the hypothesis that adenosine potentiates both the airway narrowing and the release of bronchoconstrictor mediators induced by ovalbumin challenge in sensitized guinea pigs.


METHODS
After ovalbumin sensitization, 4 groups were studied: control group, adenosine group (ADO), ovalbumin group (OA), and adenosine plus ovalbumin group (ADO + OA). Changes in airway resistance were assessed from continuously recorded pulmonary insuffilation pressure (PIP). The concentration of histamine, PGD2, and thromboxane B2 were determined from bronchoalveolar lavage fluids.


RESULTS
Adenosine alone (6 mg/kg intravenously) did not influence baseline values of PIP and the mediator concentrations; however, ovalbumin (10 mg/kg intravenously) increased both the PIP and the levels of the measured mediators compared with the control and ADO groups. When ovalbumin challenge was preceded by adenosine administration, both PIP and mediator levels were significantly enhanced compared with values obtained after simple ovalbumin provocation (ADO + OA vs OA: P <.05).


CONCLUSIONS
These results suggest that adenosine potentiates the airway narrowing induced by ovalbumin challenge and that this effect may develop through facilitation of the release of bronchoconstrictor mediators during the immediate airway response.
Huszár
E
E
Department of Pathophysiology, National Korányi Institute for TB and Pulmonology, Budapest, Hungary.
Horváth
I
I
Barát
E
E
Herjavecz
I
I
Böszörményi-Nagy
G
G
Kollai
M
M
D000241:Adenosine / Q000097:blood*; D000818:Animals; D001985:Bronchial Provocation Tests; D001986:Bronchial Spasm / Q000209:etiology*; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry; D016085:Bronchoconstrictor Agents / Q000378:metabolism*; D006168:Guinea Pigs; D006632:Histamine / Q000032:analysis; D006801:Humans; D010047:Ovalbumin / Q000276:immunology; D015230:Prostaglandin D2 / Q000032:analysis; D013929:Thromboxane B2 / Q000032:analysis
D016085:Bronchoconstrictor Agents; D013929:Thromboxane B2; D006632:Histamine; D010047:Ovalbumin; D000241:Adenosine; D015230:Prostaglandin D2