Atypical ion channel radius is about 1 nm (nanometer), and the thickness of the cell membrane is about 7 nm. the concentration of na+ ions inside a mammalian heart cell is about 0.6 ions/nm3, and in the fluid surrounding the cell is about 6.0 ions/nm3. the diffusion constant for ions is about 109 nm2/s (nanometers2/second). if the channel were just an open cylinder, how many ions per second would flow through the channel?