Figure 5.

Events of mixed propagation imaged at high temporal resolution in frog muscle. Video rate line scan images of fluorescence in “sulfate/low Ca²⁺,” with color scale shown between B and C. (A) A sequentially propagated event. (B) A mixed event, in which sequential activation (dashed line) alternates with sudden increases in fluorescence (arrows). The image is repeated at right in a compressed time scale, to show that the sudden increases result in rapid widening, followed by transient interruption of propagation (bracket). (C) Examples of events in which a local increase in fluorescence accompanies a stop in propagation. (D) An event with a stop and no intensification of fluorescence (a second example is in A). (E) Events where increases in fluorescence do not stop propagation. (F) Example of propagated events that have neither interruptions of propagation nor increases in intensity. Identifiers: A and B, 091102c93, 104; C, 090502c, 091002a, 091102c; D, 091102c33; E, 091102c32, 36, 83; F, 091102c92.