Cytosolic Ca++ concentration typically rise about 40-fold when Ca++ channels open in the plasma membrane. Assume that 1000 Ca++ channels open in a cell with a volume of 1000 micrometer cube and an internal Ca++ concentration of 100 nM. Each Ca++ channel passes 1,000,000 Ca++ ions per second. How long would the channels need to stay open in order to raise the cytosolic Ca++ concentration from 100 nM to 4 microMoles?