Autonomic NS 3 Flashcards
Tyrosine hydroxylase
– Rate limiting step
- inhibited by catecholamines
DOPA decarboxylase
– Methyldopa
hypertension in pregnancy
Dopamine β-hydroxylase (DBH)
– Membrane bound
PNMT
- mainly located in adrenal medulla
- induced by adrenal cortex hormones
Noradrenaline (NA) release
this is facilitated by ca2+
α2 adrenoreceptors on the presynaptic terminal
– ↓Ca2+influx therefore ↓NArelease
norepinephrine transporter
NET
“repackaged” by vesicular monoamine transporter
VMAT
what is noradrenaline uptake and degradation affected by
indirectly acting sympathomimetic drugs
monamine oxidase (MOA) inhibitors
Uptake inhibitors
Drugs that affect catecholamine synthesis
methyldopa
Drugs that affect catecholamine release
- Indirectly acting sympathomimetics – e.g. amphetamines
- By acting on α2 adrenoreceptors – e.g. clonidine
Inhibitors of catecholamine uptake
NET inhibitors – e.g. cocaine, tricylic antidepressants
Inhibitors of catecholamine metabolic degradation
Monoamine oxidase inhibitors used in depression
What are the two main groups of adrenoreceptors
alpha 1 and 2
beta 1, 2 and 3
Adrenergic receptors are
metabotropic (G-protein coupled receptors)
Nasal congestion
Phenylephrine
Constriction of airway blood vessels (α1)
Asthma
Salbutamol = short acting
Salmeterol = long acting
Also terbutaline
All cause bronchodilation
mean arterial blood pressure =
cardiac output x total peripheral resistance
Sympathetic stimulation increases cardiac output by
– Byincreasingtheheartrate
– By increasing the volume pumped on each stroke
– Both mediated by β1 receptors
Sympathetic stimulation increases total peripheral resistance
– By constricting blood vessels (mainly small arteries/arterioles)
– Mediated by α1 receptors
Cardiogenic shock
Damaged heart, unable to supply enough blood to the organs of the body
Dobutamine
↑ heart rate and force
Hypertension
Elevated blood pressure
Prazosin
Propranolol
Atenolol
Clonidine
Anaphylaxis
Narrowing of airways
Sudden drop in blood pressure
Red raised itchy skin rash
Swelling of eyes, lips, hands and feet
Benign prostatic hyperplasia
Swollen prostate causing problems with passing urine
- Prazosin
- Relax bladder neck and prostate capsule by blocking α1 receptors
- Tamsulosin is more prostate-specific