Adrenergic Nervous System/
Sympathetic Nervous System/
Thoraco-lumbar
SYMPATHOMIMETICS/
ADRENERGIC DRUGS
, Introduction
• First time suggested by Sir Henry Dale
• Wide distribution
• Adrenergic neurons are also present in CNS
(hypothalamus and reticular formation)
• Three endogenous catecholamines
(Catechol nucleus + an amine)
Eg. Adrenaline (Epi), Nor-adrenaline
(NE), Dopamine (DA)
• Isoprenaline is not endogenously present (Benzene ring with
2 adjacent OH groups)
in the body
, Noradrenergic transmission
• Adrenaline: It is secreted by adrenal medulla
and also have transmitter role in the brain
• Nor-adrenaline: Act as NT at post ganglionic
sympathetic sites
• Dopamine: Major NT in basal ganglia, limbic
system, CTZ, anterior pituitory etc.
• Isoprenaline: Synthetic derivative of NA; not
found in the body
, History of NA
• Oliver and Schaffer (1895) first reported that injection of
extracts of adrenal glands in cat increases BP
• Takamine (1901) purified active principle of adrenal
gland and named it as ADRENALINE
• Henry Dale (1906) observed in anesthetized cat that the
rise in BP by iv injections of ADR could be changed to
fall in BP on pre-treatment with ERGOT.
“VASOMOTOR REVERSAL OF DALE”
• This experiment showed that ADR caused two distinct
effects i.e. vasoconstriction and vasodilatation. This effect
give rise to the concept of different sets of receptors for
Adrenergic NS.
• Ergot blocked vasoconstrictor effect (α1) without
interfering with vasodilatation effect (β2)
Sympathetic Nervous System/
Thoraco-lumbar
SYMPATHOMIMETICS/
ADRENERGIC DRUGS
, Introduction
• First time suggested by Sir Henry Dale
• Wide distribution
• Adrenergic neurons are also present in CNS
(hypothalamus and reticular formation)
• Three endogenous catecholamines
(Catechol nucleus + an amine)
Eg. Adrenaline (Epi), Nor-adrenaline
(NE), Dopamine (DA)
• Isoprenaline is not endogenously present (Benzene ring with
2 adjacent OH groups)
in the body
, Noradrenergic transmission
• Adrenaline: It is secreted by adrenal medulla
and also have transmitter role in the brain
• Nor-adrenaline: Act as NT at post ganglionic
sympathetic sites
• Dopamine: Major NT in basal ganglia, limbic
system, CTZ, anterior pituitory etc.
• Isoprenaline: Synthetic derivative of NA; not
found in the body
, History of NA
• Oliver and Schaffer (1895) first reported that injection of
extracts of adrenal glands in cat increases BP
• Takamine (1901) purified active principle of adrenal
gland and named it as ADRENALINE
• Henry Dale (1906) observed in anesthetized cat that the
rise in BP by iv injections of ADR could be changed to
fall in BP on pre-treatment with ERGOT.
“VASOMOTOR REVERSAL OF DALE”
• This experiment showed that ADR caused two distinct
effects i.e. vasoconstriction and vasodilatation. This effect
give rise to the concept of different sets of receptors for
Adrenergic NS.
• Ergot blocked vasoconstrictor effect (α1) without
interfering with vasodilatation effect (β2)
