A neurohormone of cephalopods with cardioexcitatory activity

A neurohormone (NS) with long-lasting cardioexcitatory action on the isolated heart of cephalopods, has been extracted from the neurosecretory system of the vena cava (NSV system) of several cephalopod species. Electrical stimulation of the NSV nerves to the vena cava liberated a cardioexcitatory substance. Cardioexcitor extracts from Octopus vulgaris have had their activity increased 95 times by purification procedures. The resulting material is homogeneous on electrophoretic analysis, shows an absorbance maximum near 265 nm, and has a molecular weight of about 1300. NS is not identifiable with any catecholamine or indole compound known to be present in cephalopod tissues.