Down-regulation of IP3R1 mass by injection of adenophostin A (AdA) reduces/eliminates [Ca2+]i responses induced by SrCl2. Injection of AdA induces dose-dependent down-regulation of IP3R1 in mouse oocytes (A). Down-regulation of IP3R1 mass by injection of 2 μM AdA did not affect the number of eggs capable of initiating [Ca2+]i oscillations when exposed to SrCl2 (B, right part, left trace), although injection of 5 μM AdA significantly decreased the number of eggs responding to SrCl2 (right part, center traces), and injection of 10 μM AdA nearly abolished responses in all injected eggs (right part, right trace). A representative [Ca2+]i trace of a control egg is shown in the left part.