Although the externally controllable extracellular supply of the short-lived reactive oxygen and nitrogen species, such as O-2(center dot-), (NO)-N-center dot, and ONOO-, could potentially manipulate cellular functions, their simple administration to cells is likely to be ineffective due to their rapid deactivation. In this study, we found a method of a continuous supply of O-2(center dot-)/ONOO- over a few minutes, which is triggered by irradiation of a nonequilibrium atmospheric pressure plasma to commonly used organic buffers (e.g., 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid, HEPES). In addition, a continuous low-dose O-2(center dot-)/ONOO- supply was shown to induce a physiologically relevant Ca2+ response and subsequently the uptake of a large cation mediated by transient receptor potential channel family member(s). Our results provide a novel approach to the continuous O-2(center dot-)/ONOO- supply, requiring controllable and mass-volume treatments.