Figure 1
Circuit diagram for the single chain of ten smooth muscle cells bathed in a bath of Ringer solution. Only the two ends of the strand are depicted so that the circuit components can be seen more clearly. Electrical stimulation (0.25 nA, 0.5 ms rectangular current pulses) was applied to the inside of the first cell (cell #1). The AP propagated from the stimulated cell #1 down the entire chain. A variable shunt resistance (Rgj) was inserted across each of the nine cell junctions to reflect various numbers of gap-junction channels (0, 1, 10, 100, 1,000, and 10,000). The radial resistance of the very narrow junctional clefts (Rjc) is depicted. Each smooth muscle cell is depicted by four basic units: two for the surface membrane (one upward-facing and one downward-facing) and one for each of the two end junctional membranes. To reduce complexity, the transmembrane voltage (Vm) was recorded from only the upward-facing surface membrane.