Before revision:  Assuming  the activation sensors are independent and the activation variable m has a faster relaxation than the inactivation variable h, the open state probability during the action potential may be expressed as m(t) ^3 h(t) , and the  kinetic equations may be  reduced to rate equations for activation, and  fast and slow inactivation that describe spike frequency adaptation  in the neural membrane, a repetitive bursting oscillation and a cardiac action potential with a plateau oscillation.
After revision:  Assuming the activation sensors are independent and the activation variable m has a faster relaxation than the inactivation variable h, the open state probability during the action potential may be expressed as m(t) ^3 h(t) , and the rate function for entry into the slow inactivated state is dependent on the fast inactivation variable. The kinetic equations may be reduced to rate equations for activation, and fast and slow inactivation that describe spike frequency adaptation in the neural membrane, a repetitive bursting oscillation and a cardiac action potential with a plateau oscillation.