Adenosine A1 antagonism attenuates atropine-resistant hypoxic bradycardia in rats.

Objectives: To test the following hypotheses: Hypoxia induces bradycardia and hemodynamic compromise that are resistant to atropine but responsive to selective antagonism of the adenosine A1 receptor (A1AdoR). The mechanism for such attenuation is independent of the vagus nerve.

Methods: Ten minutes after sham or actual bilateral cervical vagotomy, paralyzed ventilated rats were made hypoxic (5% fractional inspired oxygen, continued until death).