Histamine

Front 1

Histamine range found in Mammalian tissues

Back 1

<1 - >100 microgram/g

Front 2

Chemical Nature of Histamine

Back 2

Hydrophilic

Front 3

Receptors of Histamine

Back 3

H1, H2, H3, H4

Front 4

Receptor analogs (Preference)

Back 4

H1 ---> 2-methylhistamine

H2----> 4(5)-methylhistamine

H3---> Histamine's chiral analog: (R) -alpha- methylhistamine

H3, H4 (a number of compounds work at both)

(R) - Alpha methylhistamine is a weak agonist of H4

Front 5

Storage site of histamine

Back 5

Mast cells usually.

Basophils in blood

Front 6

Histamine synthesis

Back 6

Histamine is formed by decarboxylation of the amino acid histidine by the enzyme L-histidine decarboxylase

Front 7

How do Basophils and mast cells store histamine?

Back 7

In secretory granules

Front 8

PH & chemical characteristics of histamine at secretory granules

Back 8

~5.5, +ve charged and complexed w negatively charged acidic groups in proteases & heparin or chondroitin sulfate proteoglycans

Front 9

Which tissues are capable of histamine synthesis?

Back 9

Every mammalian tissue that contains histamine is capable of synthesizing it. eg, neurons, mast cells, gastric mucosa, epidermis

Front 10

Are there any non mast cell storage sites of histamine?

Back 10

CNS, epidermis, gastric mucosa, cells in regenerating or rapidly growing cells.