Histamine Causes:
Stimulation of H1
Receptors
n
Contraction of smooth muscle
à
Wheeze
n
Stimulation of Vagus
à
Cough
n
Permeability veins
à
Edema
n
Vasodilation
à
Flushing
n
secretions
à
Mucous
n
Stimulation of nerve endings
à
Pruritus
Stimulation of Vagus causes bronchoconstriciton which is seen by the patient coughing