# Calcium concentration in NMDARs e Nitric Oxide Synthase

My question is related to calcium $\ce{Ca^{2+}}$ concentration in NMDA receptors and nitric oxide synthase. I've found a very simple model that describes how the time change of calcium can be related to the NMDA current (http://www.pnas.org/content/98/22/12772.full.pdf, Appendix B), but, however, I would like to find some relationships between the time derivative of $\ce{NO}$ concentration and the time derivative of $\ce{Ca^{2+}}$.

Does exist an expression that could solve this problem?