RT Journal Article SR Electronic T1 Multiple modulators act on the cardiac ganglion of the crab, Cancer borealis JF Journal of Experimental Biology JO J. Exp. Biol. FD The Company of Biologists Ltd SP 2873 OP 2884 DO 10.1242/jeb.002949 VO 210 IS 16 A1 Cruz-Bermúdez, Nelson D. A1 Marder, Eve YR 2007 UL http://jeb.biologists.org/content/210/16/2873.abstract AB Neuromodulators can change the output of neural circuits. The crustacean cardiac ganglion (CG) drives the contractions of the heart. The CG is a direct target for neurohormones that are released from the pericardial organs and other neuroendocrine sites. In this study, we have characterized for the first time the physiological actions of the peptides red pigment concentrating hormone (RPCH), Cancer borealis tachykinin-related peptide Ia (CabTRP Ia) and allatostatin III type A (AST-3) on the isolated CG of the crab, Cancer borealis. RPCH and CabTRP Ia excited the CG while AST-3 strongly inhibited its motor output. We also studied the actions of other peptides and small molecule transmitters known to be present in C. borealis. Dopamine, serotonin, proctolin, crustacean cardioactive peptide (CCAP), a number of extended FLRFamide peptides, and cholinergic agonists increased the activity of the CG, GABA inhibited the CG, while other substances had little or no significant effect on the CG motor pattern. These results demonstrate, in one species, that the CG is multiply modulated. We suggest that multiple modulators may be important to regulate and coordinate the activity of the heart and other organs in response to external stimuli or the endogenous physiological state.