Vasoactive amines

Pathology

1. VASOACTIVE AMINES

2. Definition
A substance containing amino
groups that acts on blood vessels to
alter their permeability.

3. Two vasoactive amines –Histamine and
serotonin.
Stored as preformed molecules in mast cells
and other cells.
First mediators released in acute
inflammation.

5. HISTAMINE
Produced mainly by mast cells.
Also by circulating basophilsand platelets.

6. SYNTHESIS
Decarboxylationof histidineby the
enzyme histidinedecarboxylase.

7. Histamine released from mast cell
granules in response to :
1.Physical injury such as trauma or
heat.
2.Immune reactions involving
binding of IgEantibodies to Fc
receptors on mast cells.

8. 3.C3a and c5a fragments of complements
called anaphylatoxins.
4.Leukocyte derived histamine releasing
proteins.
5.Neuropeptides(substance P)
6.Cytokines( IL1,IL8)

9. Actions of Histamine
Vasodilation.
Increase vascular permeability by inducing venular
endothelial contraction and formation of
interendothelial gaps.

10. Serotonin
5-hydroxy tryptamine.
Biochemically derived from tryptophan
Found in platelet granules.
Also found in neurons and enterochromaffin
cells.

11. Released in response to platelet
aggregation
Serotonin from enterochromafin
cells blood taken up by
platelets and stored released
during aggregation

12. Actions of serotonin
Vasoconstriction during clotting.
Neurotransmitter
Regulates intestinal motility.

13. Thank
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