reversal action of acetylcholine on blood pressure in dog
TRANSCRIPT
Reversal action of Ach on Blood prerssure
By Dr. Sameh AM Abdelghany
Chemical transmitters in PSNS
Acetylcholine(Ach):
Synthesis and storage:
• Choline + Acetyl CoA → Acetylcholine + CoA
Sites of release in ANS:
1. All autonomic ganglia.
2. All postganglionic parasympathetic fibers.
3. Postganganglionic sympathathetic fibers to sweat
glands.
4. Suprarenal medulla.
Fate:
• by cholinesterase (ChE) enzyme
Cholinergic receptors
Muscarnic receptors Nicotinic receptors
• Site - Effector organs supplied by
parasympathetic
- Sweat glands , Blood vessels
- CNS(Brain only)
- Autnominc ganglia (Nn)
- Adrenal medulla (Nn)
- Motor end plate(Nm)
- CNS spinal cord mainly (Nn)
• Subtypes M1, M2, M3, m4,m5 Nn , Nm
• Blockers Atropine - Ganglion blockers
- Neuromuscular blockers
Parasympathomimetics
Parasympathomimetics
Direct
Choline esters
e.g A.Ch
Alkaloids
e.g Pilocarp0ine
Indirect
Reversible
e.g Physostigmine
Irreversible
e.G Parathion
Muscarinic actions
Eye:-
Miosis due to stimulation of M receptors in constrictor
pupillea ms
Contract ciliary ms that leads to accommodation for near
vision
Secretions:
Increase salivary , bronchial , gastric acid and sweat
secretions
Respiratory system
Bronchospasm
Increase bronchial secretions
CVS:
Heart : ↓ all cardiac properties COP
Blood vessels: VD PR
Blood pressure: decrease BP(Hypotension)
due to:
i. Generalized VD of BV.
ii. ↓ COP
Reversal action of AcH on blood pressure:
Stimulation of M receptors in heart and blood vessels produce decrease in blood
pressure. After block of M eceptors by atropine, then nicotininc receptors stimulation
in sympathetic ganglia and adrenal medulla release endogenous catecholamines
which produce elevation in blood pressure
GIT:
Increase motility
Urinary tract:
Contract wall and relax sphincters
Nicotinic effects
At Neuromuscular junctions
muscle twitches
Stimulation of all autonomic ganglia
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