Drugs acting in the Sympathetic system Flashcards
What is the effect of drugs in the sympathetic nervous system?
- Increased HR
- Bronchodilation
- Inhibition of mucus secretion
- Increased sweating
- Decreased motility/inhibition of secretion
- Release of adrenaline
- Relaxation of detrusor muscles. contraction of sphincter = decreased micturition
What is the process of neurotransmission in adrenergic receptors?
- Adrenergic receptors - transmission of noradrenaline from adrenergic receptors to postganglionic neuron in vesicles
- Nicotinic ach receptors
- ACH in vesicles
What are the subtypes of adrenergic receptors?
- Alpha and Beta adrenergic receptors
- Relative potency in alpha= adrenaline>noradrenaline>isoprenaline
- a1-adrenergic receptors
-a2- adrenergic receptors - Relative potency in Beta =
isoprenaline> adrenaline> noradrenaline - B1 - adrenergic receptors = adrenaline = noradrenaline
-B2 -adrenergic receptors adrenaline> noradrenaline
What organs are adrenergic receptors found in?
- Heart - B
- Lungs - B2
- Gut - A1 and B1
- Blood vessels - a1 and B2
What is the adrenergic control in the heart?
- B1 receptors are coupled to Gs G protein (signal via cAMP) and increase HR and force of contraction of cardiac muscle
What effect do adrenaline and noradrenaline have on heart rate and force of contraction.
- Increase HR and force of contraction
- Leads to an increase in Ca 2+ through channels (Protein Kinase A has an effect in doing this)
- Influx of Na+ leads to an increased rate of contraction of the heart
- Adenyl cyclase converts ATP into cAMP to PKA
What effects do Beta antagonists have on HR?
Decrease HR
How does adrenaline cause bronchodilation?
B2 G protein splits apart - adenyl cyclase
- Adenyl cyclase converts ATP into cAMP
- cAMP to PKA to myosin light chain kinase = relaxation of smooth muscle
What are some cons of using a B2 agonist for bronchodilation?
- Adrenaline does not last long
- Has effects on the heart
Compare salbutamol and salmeterol
- Salbutamol lasts for 4-6 hrs
- More resistant to metabolism by COMT( Catechol-O-methyltransferase
- More resistant to metabolism by MAO ( monoamine oxidase)
Salmeterol = 12h
What are some examples of drugs that interfere with NA reuptake?
- Cocaine and amphetamine
- Remove noradrenaline from the cleft and puts it back in the cytoplasm to be packed into vesicles/broken down by enzymes
What are some unwanted effects of cocaine and amphetamine?
Heart - Increased HR and force of contraction
Blood vessels- Constrict (dilate)
- Kidney- release renin - fluid volume
- urinary bladder – relaxes detrusor muscle, contracts sphincter muscles - urinary retention
