Increase of Plasma Substance P- and Neurokinin A-Like Immunoreactivity During Carcinoid Flushing

The biochemical agent(s) responsible for the carcinoid flush is still unknown. During 3 episodes of carcinoid flush induced by physical effort the following changes were observed in plasma: a) increase of substance P-like immunoreactivity; b) a minor rise of neurokinin A-like immunoreactivity; c) no change of blood and plasma serotonin. HPLC analysis of plasma extracts collected after the administration of streptozocin, inducing long lasting flushing, showed a marked increase of NKA and of substance P-like material and a minor rise of SP. It is proposed that these compounds take part in the pathogenesis of carcinoid flush.