Effect of intranasal histamine challenge on Eustachian tube function.

OBJECTIVE

To show a relationship between intranasal histamine challenge, the development of middle ear effusion and Eustachian tube (ET) dysfunction in a rat model.

METHODS

Non-allergic Sprague-Dawley rats weighing between 450-600 g were randomly assigned to receive an intranasal infusion of 16 microl of 10% histamine or normal saline. ET function was assessed by using the forced-response test to measure passive and active opening and closing pressures at time intervals of 6, 10, 14, 18, 22, and 26 min and 24 h post-infusion. Mucociliary clearance times (MCCTs) of the tubotympanum at 18 min post-infusion were measured by timing the transit of dye from the middle ear to the nasopharynx. Outcome measures were ET dysfunction and evidence of clinical effusion.

RESULTS

Intranasal histamine caused acute ET dysfunction when introduced into the nasopharynx demonstrated by significant elevations in passive and active opening and closing pressures (P < or = 0.001) compared to controls. The largest difference was seen at 26 min post-infusion. Furthermore, MCCTs were 2.4 times longer after infusing intranasal histamine than after saline infusion. No clinically significant effusions were evident in either group at any time interval.

CONCLUSION

These data demonstrate a successful development of an intranasal histamine rat model, in addition to a relationship between intranasal histamine challenge and development of acute ET dysfunction.