The spontaneous burst discharges of isolated lobster (Homarus americanus) cardiac ganglia were recorded with a spaced array of electrodes. Small regions (less than 1 mm) of the ganglion were exposed to the cardioexcitor neurohormone in extracts of pericardial organs (XPO) or to 10(−5) M 5-hydroxytryptamine (5HT). All axons were excited (increased mean firing frequency, f) by both substances, but only by applications in the region between the soma (but excluding it) and proximal site of impulse initiation. Units not so exposed changed their f relatively little despite f increases of as much as threefold in exposed units and changes in burst rate and overall length. Regularity and grouping of all impulse activity into bursts was never disturbed. 5HT increases burst rate at any point of application. The increases are larger if small cells are affected than if only large cells are exposed. Burst length decreases except when the pacemaker is affected. In contrast, XPO affects neither burst rate or length unless small cells are affected. Length is increased if non-pacemaker small cells are affected; both rate and length increase if the pacemaker is affected. The pacemaker usually exhibits an f of intermediate value. Rate changes are not simply related to its f. A small cell can “burst” in the absence of impulses from any other cells. XPO may enhance endogenous “driver potentials,” while 5HT may excite by depolarizing at limited sites.
Neurohormonal alteration of integrative properties of the cardiac ganglion of the lobster Homarus americanus
I. M. Cooke, D. K. Hartline; Neurohormonal alteration of integrative properties of the cardiac ganglion of the lobster Homarus americanus. J Exp Biol 1 August 1975; 63 (1): 33–52. doi: https://doi.org/10.1242/jeb.63.1.33
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Meet the JEB Editors @ SEB 2023
Come and meet the JEB team at the Society for Experimental Biology centenary conference from 4-7 July in Edinburgh, UK. Visit exhibition stand 13/15 to pick up JEB centenary goodies, including our new ‘100 years of discovery’ T shirt, and join our Meet the JEB Editors event on Thursday 6 July at 12.30 at Platform 5 to find out more about the journal and chat to Editors including EiC Craig Franklin, Monitoring Editors Sanjay Sane, Trish Schulte and John Terblanche and the in-house News and Reviews team.
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JEB@100: an interview with Monitoring Editor Katie Gilmour
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The Forest of Biologists
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Centenary Review - Adaptive echolocation behavior
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