Effects of perfusion pressure on the bursting neurons in the intact or segmented cardiac ganglion of the lobster, Panulirus japonicus.

Impulse activity of the bursting neurones in the intact or segmented cardiac ganglion could be recorded in the isolated and freely beating hearts of lobsters. In the segmented ganglion, the four large cells (LCs), the medium cell (MC), and the four small cells (SCs) generated phasic, short tonic, and long tonic bursts of impulses with different rhythms, respectively. The periodic bursts of the LCs, the MC, and the SCs in the intact and the segmented ganglia were perturbed by a change of heart tonus which reflected a change of perfusion pressure in the heart. When correlation between period and duration of the perturbed bursts was plotted, the LCs, the MC, and the SCs in the segments were different from one another in distribution of the plots. Further, the correlation plots for the bursts of the MC in the intact ganglia were compared to those of the LCs, the MC, and the SCs in the segmented ganglia. The burst period and duration of the MC in the intact ganglion were altered markedly by a change of the burst period of the LCs and the burst duration of the SCs, as well as by change of heart tonus.