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Related to thrombotonin: Thrombospondin
A vasoconstrictor, liberated by blood platelets, that inhibits gastric secretion and stimulates smooth muscle; present in relatively high concentrations in some areas of the central nervous system (hypothalamus, basal ganglia), and occurring in many peripheral tissues and cells and in carcinoid tumors.
[sero- + G. tonos, tone, tension, + -in]
n See serotonin.