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Circulating Tachykinins (Substance P, Neurokinin A, Neuropeptide K) and the Carcinoid Flush

1987; Taylor & Francis; Volume: 22; Issue: 1 Linguagem: Inglês

10.3109/00365528708991864

1502-7708

J. Michael Conlon, Carolyn F. Deacon, G. Richter, F. Stöckmann, W. Creutzfeldt,

Neuroendocrine regulation and behavior

Antisera of defined regional specificity have been used to measure the concentration of substance P-like immunoreactivity (SP-LI) and neurokinin A-like immunoreactivity (NKA-LI) during a meal-induced flush in 10 patients with metastatic carcinoid tumours. Although all patients flushed, NKA-LI levels in five patients and SP-LI in six patients were not elevated relative to healthy subjects (NKA-LI, < 3 pg/ml; SP-LI, < 10 pg/ml) both in the fasted state and after food. In the patients with elevated basal plasma tachykinin levels, increases in NKA-LI and SP-LI after food were erratic and did not correspond to a defined digestive phase or the occurrence of the flush. Chromatographic analysis of plasma demonstrated the presence of neuropeptide K and neurokinin A, and the detection of COOH-terminal fragments of substance P is consistent with the higher levels of circulating SP-LI measured with a COOH-terminally directed antiserum compared with an NH,-terminally directed antiserum. Subcutaneous injection of the somatostatin analogue SMS 201–995 (50 μg) alleviated symptoms of flush in two of three patients but only partially suppressed NKA-LI and SP-LI concentrations. It is concluded that circulating tachykinins cannot be solely responsible for the meal-induced carcinoid flush.