central action of octopamine on ventilation frequency in Corydalus cornutus

Application of octopamine (10−4 or 10−5 M) to ventrally dissected hellgrammites increased the frequency of the ventilatory rhythm 16.6 ± 2.0%. Similar results were observed when a chain of abdominal ganglia was isolated from other parts of the central nervous system and the periphery; thus, the effect was a central one. A ventilatory increase of similar magnitude was not elicited from chains of ganglia that lacked the dominant oscillator for the ventilatory rhythm; thus, exogenous octopamine acts at the expected site of physiological control of the rhythm. Dopamine (10−4 or 10−5 M) decreased ventilatory frequency 16.7 ± 4.0%. Thus, as in other animals (Livingstone et al., '80), a pair of amines has opposite effects on an invertebrate behavior.