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Platelet 5-hydroxytryptamine storage in the carcinoid syndrome
American Journal of Clinical Pathology
|October 1, 1978
Summary
Human platelets store serotonin (5-hydroxytryptamine) in multiple locations, including membranes and alpha granules. Carcinoid syndrome patients show altered serotonin storage patterns in platelet cytoplasm and dense bodies.
Area of Science:
- Biochemistry
- Cell Biology
- Hematology
Background:
- Platelets play a crucial role in hemostasis and inflammation.
- 5-hydroxytryptamine (serotonin) is a key neurotransmitter and signaling molecule.
- Altered serotonin metabolism is observed in conditions like carcinoid syndrome.
Purpose of the Study:
- To investigate the uptake and storage mechanisms of 5-hydroxytryptamine in human platelets.
- To compare serotonin storage in platelets from healthy donors and patients with carcinoid syndrome.
Main Methods:
- Incubation of human platelets with radiolabeled 3H-5-hydroxytryptamine.
- Quantitative analysis of serotonin uptake.
- Electron microscopic autoradiography to localize serotonin within platelet compartments.
Main Results:
- Platelets exhibit rapid initial uptake of 5-hydroxytryptamine, followed by slower accumulation.
- In normal platelets, 5-hydroxytryptamine is primarily localized in membranes, alpha granules, and cytoplasm.
- Platelets from carcinoid syndrome patients show similar membrane and alpha-granule labeling but increased cytoplasmic and decreased dense-body labeling.
Conclusions:
- Human platelets possess multiple sites for 5-hydroxytryptamine storage.
- Carcinoid syndrome is associated with altered distribution of 5-hydroxytryptamine within platelet compartments.
- Evidence suggests limited exchange between cytoplasmic and dense-body serotonin in carcinoid platelets.