Ventilatory response to cholecystokinin tetrapeptide in anaesthetized dogs

Cholecystokinin (CCK) has been implicated in the genesis of panic disorder. In this study we measured the ventilatory response to i.v. injection of CCK-tetrapeptide (CCK-4) in anaesthetized dogs. We found an immediate and transient increase in minute ventilation. The response was large (more than 100% of baseline) and lasted 1-2 min. Repeated CCK-4 injection produced a somewhat reduced response, suggestive of a slight degree of tachyphylaxis. Blood pressure and heart rate changed only slightly (<10%), while respiratory mechanical parameters remained unchanged following CCK-4 administration. We conclude that CCK-4 has a significant effect on ventilation in the anaesthetized dog, which suggests that this species may provide a useful quantitative assay for the anxiogenic effects of CCK.