Patterns of conduction in smooth muscle.

Abstract

In sheets of circular intestinal muscle, electrical waves conduct in all directions, much faster and with less decrement in the long than in the transverse axis of the fibers. Need for interfiber summation is shown by failure to initiate conducted spikes with stimulating electrodes less than 100 µ diameter. Conduction is in bands with occasional entry from one band into another. Minimal latency occurs in a 1–2-mm band in line with stimulating electrodes. Diagonal conduction was not observed, but double spikes represent direct conduction followed by re-entry into a band from a parallel conducting path. Records with double microelectrodes, 1–700 µ apart, showed no measurable latency difference when both were in the same fiber but normal velocity at separations greater than 50 µ.