Lethality was associated with high-molecular weight material. Post-mortem examination revealed no tissue or vascular damage except in the lungs where vascular damage, constricted alveoli and oedematous septae were evident. In addition, large accumulations of erythrocytes were observed in alveolar capillaries, suggesting blood flow through the lungs had been reduced by obstruction of the pulmonary arteries. Temple-Smith also demonstrated that the venom contains hyaluronidase and proteolytic activities. This appears to be the effect of a natriuretic peptide in the venom.
Natriuretic peptides are a family of peptides which are highly conserved between species.
The natriuretic peptides, including the platypus form, elevate cyclic GMP in vascular smooth muscle, resulting in vasodilatation. It is thus possible that the platypus natriuretic peptide is responsible for the hypotensive effect of the venom in experimental animals described above. These findings, in addition its aforementioned effects and discovery in platypus and pit viper venom, implies a pathophysiological function. Unfortunately, it is impossible to gain access to and electrical control over nociceptive terminals in the periphery to address this question directly. Instead, the cell bodies of nociceptive neurones which are found in sensory ganglia may be used as a model of the nociceptor terminal.