Infusion of inositol-3,4,5,6-tetrakisphosphate (Ins(3,4,5,6)P4) from the patch pipette into the cytoplasm, produced a biphasic intracellular free Ca2+ concentration ([Ca2+]i) increase in ras-transformed NIH/3T3 (DT) cells. The Ins(3,4,5,6)P4-induced increase in DT cells depended upon extracellular Ca2+ and was enhanced by membrane hyperpolarization. Identical [Ca2+]i increases were observed with intracellular application of inositol-1,3,4,5-tetrakisphosphate (Ins(1,3,4,5)P4) and inositol-1,3,4,6-tetrakisphosphate but not with inositol-1,2,4,5-tetrakisphosphate, inositol-1,4,5-trisphosphate or inositol-1,3,4,5,6-pentakisphosphate. Stimulation of DT cells with bradykinin increased the levels of Ins(3,4,5,6)P4 and Ins(1,3,4,5)P4. These results suggest that Ins(3,4,5,6)P4 may serve as a second messenger for continuous Ca2+ influx along with other tetrakisphosphates downstream from bradykinin receptors in DT cells.
All Science Journal Classification (ASJC) codes
- Structural Biology
- Molecular Biology
- Cell Biology