Figure 10. The combination of InsP₃ and thapsigargin evokes a robust secretory response in weak buffer, whereas InsP₃ alone is largely ineffective.

InsP₃ alone (•) or in combination with GTPγS (▵) did not trigger a detectable increase in membrane capacitance, whereas InsP₃ together with thapsigargin and GTPγS produced a prominent secretory response (○). In these experiments, cells were clamped at −60 mV.