Monitoring biological membrane-potential changes: a CI QM/MM study.

In recent decades, new less-invasive, nonlinear optical methods have been proposed and optimized for monitoring fast physiological processes in biological cells. One of these methods allows the action potential (AP) in cardiomyocytes or neurons to be monitored by means of second-harmonic generation (SHG). We now present the first, to our knowledge, simulations of the dependency of the intensity of the second harmonic (I(SHG)) on variations of the transmembrane potential (TMP) in a cardiomyocyte during an action potential (AP).