[Neural regulation of heart function in the Pteropod mollusc Clione limacina]

The heart of the pteropodial mollusc Clione limacina is innervated by the median nerve arising from the left abdominal ganglion. Five neurons sending axons to the heart have been identified in the Clione central nervous system with retrograde cobalt or Lucifer yellow staining. Neuron H1 located in the left pedal ganglion evoked heart excitation. Three neurons H2-H4 located in the medial part of the left abdominal ganglion caused heart inhibition. Neuron H5 located in the caudal part of the left abdominal ganglion did not affect the heart. The activity of the efferent heart neurons was found to be related to the operation of the locomotor rhythm generator. Spontaneous or reflex suppression of the locomotor rhythm generation was accompanied by inhibition of neuron H1 and excitation of neurons H2-H4. Such behavior of the efferent heart neurons ensures a positive correlation between heart and locomotor activities in Clione limacina.