Effect of para

Effect of parasympathomimetics on gland secretion

By
Pharmacist
Salwan Salem
8-11-2015

-Central nervous system (CNS)

- Peripheral nervous system (PNS)

*CNS: spinal cord and brain

*The PNS consists of:
sensory neurons running from stimulus receptors that inform the CNS of the stimuli

motor neurons running from the CNS to the muscles and glands - called effectors - that take action.

Nervous system

* PNS subdivided into :
Autonomic , and somatic

Autonomic NS :

- sympathatic neurons (thorasic and lumbar part of spinal cord)
- Parasympathatic neurons (cranial and sacral part of spinal cord)

1.Cardiovascular system :

-ve chronotropic effect
-ve inotropic effect
.Decrease SA and AV conductivity
.Increase IC Ca by phosphatidy inositol system
.Production of NO from arginine in endothelial cells
Pharmacological action of Ach

2. GIT:

Increase peristalsis , tone ,circulation , increase secretion , nausea and vomiting
3.Urinary tract :
Increase contraction of detrusor muscle of bladder


4. Eye miosis , and decrease IOP
5.Exocrine glands :
Increase secretion of lacrimal , salivary ,and digestive .
6.Respiratory system :
Bronchial constriction , tracheobronchial secretion

• The Cranial Nerves

•

slowing down of the heartbeat

lowering of blood pressure
constriction of the pupils
increased blood flow to the skin and viscera
peristalsis of the GI tract

Parasympathetic stimulation causes :

are neuron receptor that signal for muscular contractions . They are cholinergic receptors .
-NR found in :
1-NMJ
2-Autonomic ganglia
3-Adrenal medulla
4-ligand gated ion receptor
Nicotinic receptor agonist is nicotine .
NR Blocked by tubocurarine and doxacurium .
Cholinergic receptors :Nictonic receptors (nAch R)

Types of MR:

M1 : in CNS , Gastric parietal cells
M2: heart
M3: exocrine gland , smooth muscle, bronchia ,bladder , sweat and salivary glands.
M4 and M5 : in CNS , but function not fully understood .
Muscarinic receptors (mAch R)


1.Cardiovascular system :
-ve chronotropic effect
-ve inotropic effect
.Decrease SA and AV conductivity
.Low dose … V.D and tachycardia
.Increase IC Ca by phosphatidy inositol system
Production of NO from arginine in endothelial cells
Pharmacological action of Ach

2. GIT:

Increase perstalsis , tone ,circulation , increase secretion , nausea and vomiting
3.Urinary tract :
Increase contraction of detrusor muscle of bladder

4. Eye miosis , and decrease IOP

5.Exocrine glands :
Increase secretion of lacrimal , salivary ,and digestive .
6.Respiratory system :
Bronchial constriction , tracheobronchial secretion

. Direct acting

. Indirect acting
A -Direct acting :
Cholinesters (esters of Ach ) carbacol , bethanicol .
Alkaloids


Cholinomimitics drugsCholinergic agonists

-rarely used

- S/E : produce miosis and decrease IOP
- Has profound effect on CVS and GIT due to ganglionic stimulating activity .
- Activate N receptors in adrenal medulla .

carbacol

not Hydrolysed by AchE , while hydrolyzed by other esterases .
Used for treatment of bladder and GIT atony .

Bethanicol

Alkaloids
Is Muscarinic agonist
Mainly used in opthalmology , caused miosis
S/E : sweating and salivation because enter CNS
Pilocarpine

Reversible AchE inhibitors and irreversible AchE inhibitors .

Reversible :
1- Physostigmine :
-Act on MR , N gang , and N NMJ
-uses : GIT , bladder atonty , and glucoma .
- S/E : bradycardia , convulsions .


B-Indirect acting cholinergic drugs

2-Neostigmine

-Polar , so doesn’t pass BBB
-effect on skeletal muscle is greater than that of pysostigmine .
- used for Mysthemia Gravis , and antidote for tubocurarine .

3- Pyridostigmine :

-for long term management of M.G because of longer duration of action .
4- Edrophomium :
Used for diagnosis of M.G
-Has duration 10-12 min

- organophosphorous cpds / insectsides

- Isoflurophate
-Echothiophate
- clinically used for glucoma

Irreversible AchE inhibitors

Atropine
-causes : eye medryasis , and cycloplagia
-in low dose block M1R , cause bradycardia
-in high dose (>1 mg ) block M2R , cause tachycardia.
- dilate cutaneous vasculature

Antimuscarinic drugs

-No effect on arterial blood pressure .
-GIT: decrease motility and secretion
-urinary tract : reduce hyper motility of bladder
-secretions: decrease salivation , sweating , and lacrimal secretion .
Cont. Atropine

-antispasmodic , antidote for anticholinergic , reduce secretion prior to surgery , and cause medriasis in ophthalmology.
-other anti Muscarinic :
Scopolamine : motion sickness
Pirenzepine : gastric ulcer reduce HCL
Ipratropium : bronchodilator used for asthma .
Uses of atropine


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