Effect of CCK-4 on a 35% carbon dioxide challenge in healthy volunteers

1. The purpose of this study was to determine whether a subthreshold dose of CCK-4 would enhance the vulnerability of healthy subjects to a 35% carbon dioxide challenge. 2. 27 subjects, with no prior or present psychiatric disorder and in good physical condition were challenged with a vital capacity breath of a 35% carbon dioxide mixture, immediately after an intravenous injection of 5 micrograms CCK-4 or placebo, according to a random order double blind crossover design. 3. Subjects reported significantly less panic symptoms upon carbon dioxide after premedication with CCK-4 than after placebo. 4. Both CCK-4 and carbon dioxide may act on the same neuronal pathways, but seem to inhibit rather than potentiate each other effects.