Influence of the size of syncytial units on synaptic potentials in smooth muscle
The effect of the size of syncytial bundles of cells on the passive synaptic potentials generated within them has been explored. Computer simulations have been performed of neuronally produced spontaneous excitatory junction potentials (SEJPs) generated in a cubical 'bidomain' model of syncytial tissue. It is found that indical properties of SEJPs vary conspicuously in syncytium sizes smaller than about 15-17-cube, but change very little in syncytium sizes greater than this. At the centroid of the cube, the peak amplitude V(p) of the SEJP declines from 14.32 mV to 11.70 mV as syncytium size increases from 7-cube to 15-cube, i.e. a decrease of similar to 18%, while between system sires 15-cube (V(p) = 11.70 mV) and 29-cube (V(p) = 11.67 mV), the reduction is only similar to 0.3%. Similar trends are observed for the rime to peak of SEJPs. These observations indicate a minimum bundle size in smooth muscle below which syncytial function is modified; the implications of this are discussed.
synaptic potentials smooth muscle syncytium bidomain model electrophysiology