Abstract

The mechanical stimulation induced by poking cells with a glass needle activates Piezo1 receptors and the adenosine triphosphate (ATP) autocrine pathway, thus increasing intracellular Ca²⁺ concentration. The differences between the increase in intracellular Ca²⁺ concentration induced by cell poking and by ATP-only stimulation have not been investigated. In this study, we investigated the Ca²⁺ signaling mechanism induced by autocrine ATP release during Madin–Darby Canine Kidney cell membrane deformation by cell poking. The results suggest that the pathways for supplying Ca²⁺ into the cytoplasm were not identical between cell poking and conventional ATP stimulation. The functions of the G protein-coupled receptor (GPCR) subunits (Gα $\alpha $q, Gβ γ $\beta \gamma $), ATP-activated receptor and the upstream Ca²⁺ release signal from the intracellular endoplasmic reticulum Ca²⁺ store, were investigated. The results show that Gα $\alpha $q plays a major role in the Ca²⁺ response evoked by ATP-only stimulation, while cell poking induces a Ca²⁺ response requiring the involvement of both Gα $\alpha $q and Gβ γ $\beta \gamma $ units simultaneously. These results suggest that GPCR are not only activated by ATP-only stimulation or autocrine ATP release during Ca²⁺ signaling, but also activated by the mechanical effects of cell poking.