Differences between effect of Acetyl choline, adrenaline, Atropine

Adrenaline

Acetyl choline

Atropine

Heart:

β₁ receptors

↑ HR, ↑ force of contraction, ↑ CO (SA node)

↑ BP-followed by ↓ due to feed back regulation.

Av node-↑ conduction velocity.

Reflex bradycardia- carotid sinus compression.

Heart:

M₂ receptors

↓ Force of contraction.

SA node- hyperpolarization (bradycardia)

Av node- ↑ RP, ↑ PR interval

Delayed conduction.

Heart:

M₂- blockade—block in vagal effect.

Tachycardia.

I.m/s.c- initial bradycardia—M₁-R-autoreceptor.

Av node- ↓ RP, ↓ PR interval

↑ Conduction velocity.

Blood vessels:

α- more affinity-short time-vasoconstirction-↑ BP

β- less affinity-prolong time-vasodilation- ↓ BP

Bipolar response

Reversal of it: Dale’s vasomotor reversal.

Blood vessels:

Very less BV innervated with cholinergic transmission (salivary gland, some part of skin)

EDRF- NO- vasodilation- ↓ BP.

Blood vessels:

Tachycardia and VMC- ↑ BP.

Due to feed back regulation- ↓ BP.

CNS:

α₂ – autoreceptors

Not cross- BBB.

Not powerful CNS stimulant

Restlessness, apprehension, headache and tremor.

CNS:

Fewer drugs penetrate- BBB.

If directly given-stimulation-followed by- depression.

CNS:

High dose- medulla (stimulation)-vagal, vasomotor, VMC.

Depression- vestibular excitation-antimotion sickness.

As a anti-parkinsonian drug

Effect- irritation,restlessness, hallucination, delirium, amnesia.

-respiration dep-coma.

Glands:

Insulin secretion ↓ - β cells-  α₂ receptors

Glucagons secretion ↑- α cells- β receptors.

Saliva- scanty mucus secretion

Sweat-↓

Lacrimal secretion-↓

Glands:

↑ secretion of sweat & saliva - ↑ Ca⁺²

Glands:

↓ secretion by blocade of Ach receptors

Dryness mouth-↓ secretion.

↓ gastric secretion (Anti-ulcer)

↑ Temp- ↓ sweat

Smooth muscles:

Bronchial mus- bronchodilation by- β₂ - iinhibition of mast cell secretion & α- effect on mucosa.

Gut-relaxes-↓ motility- sphincter contracts.

Urinary bladder- detrusor muscle-relax ( β) & trigone- contract ( α)- hesitation in urination.

Smooth muscles:

Bronchoconstriction- lethal in asthma.

Gut- ↑ peristalsis- relaxes sphincter in gut.

contraction

Smooth muscles:

Relaxes-bronchodilation-histamine, eicosanoids…

Gut- ↓ motility.

Relaxation of ureter and bladder.

Eye:

Mydriasis (not given from conjuctiva)

↓ intra-ocular pressure

Eye:

Contraction-circular muscle

Contraction-ciliary muscle- ↓ i.o.p

Eye:

Mydriasis-relaxation of iris

And cyclopegia- relaxation or paralysis of ciliary muscle- paralysis accommodation of lens- ↑ FL