Calcium current to amount of substance units (mol)

[gjfelix2001]

Hi there... I have a differential equation with to terms:

\frac{d[Ca2+]}{dt}=f\Big(\frac{3I_{Ca}}{z 4 \pi r^3 F}-k_{Ca}[Ca2+]\Big)


I think that the first term converts the Ca2+ (density of?) current to mol units. But, where does it comes from?

z is the valence; in this case of the Ca2+, r is the radius of a cell, F is the Faraday's constant, and I_{Ca} is a Ca2+ current, or may be density of current. k_{Ca} is a rate with ms^{-1} units, and [Ca2+] is a concentration with mol units... In this case, r is the radius of a cell...

Thanks a lot...

 

[Borek]

Any context to that question? It is even hard to start thinking over some equation coming out of a blue.