The in uence of intrinsic channel noise on the spontaneous spiking activity of poisoned excitable membrane patches is studied by use of a stochastic generalization of the Hodgkin-Huxley model. Internal noise stemming from the stochastic dynamics of individual ion channels is known to a ect the collective properties of the whole ion channel cluster. There exists an optimal size of the membrane patch for which, solely, the internal noise causes a most regular spontaneous generation of action potentials. In addition to the variation of the size of ion channel clusters, living organisms may adopt the densities of ion channels in order to optimally regulate the spontaneous spiking activity. In our model, we selectively control via poisoning the densities of speciÿc, active ion channels. Interestingly enough, by such poisoning of some of the potassium, or the sodium ion channels, respectively, it is possible to either increase, or decrease the regularity of the spike train.