ANS Adrenergic Flashcards
acebutolol
Beta 1 selective receptor antagonists. Class II antiarrhythmic fast Na+ blocker.
TX. prohylaxis post-MI and supraventricular tachyarrhythmias. angina, HT,
less effect vasospasm, bronchospasm, uterus, metabolism.Safer in asthma, diabetes, peripheral vascular disease. ISA: intrinsic sympatomimetic activity as partial agonist with less bradycardia (-b1) and slight vaso/broncho dilation (-b2) and no change in lipids (-b2) adv. some sedation
Albuterol
Beta 2 agonist Tx asthma
Alpha 1 receptor activation effects
Gq (phospholipase C, Ip3, DAG, Ca+2) eye mydriasis: radial dilator contraction (no cycloplegia!) arterioles contraction veins contraction bladder trigone and sphincter contraction male sex organs vas deferens ejaculation liver glycogenolysis kidney DECREASED renin release
Alpha 1 effects on HR and BP
arterioles contraction veins contraction Increase TPR and BP potential bradycardia reflex CO may decrease, offset by increase venous return NO-change in pulse pressure (systolic-diastolic) *phenylephrine and methoxamine
Alpha 2 effects on HR and BP
prejunctional nerve terminals *DECREASE NE* platelets aggregation decreased CNS SANS prejunctional outflow used in mild to moderate HTN clonidine, methyldopa
Alpha 2 receptor activation effects
Gi (decrease adenylyl cyclase, cAMP) **prejunctional nerve terminals DECREASE NE release** platelets aggregation pancrease DECREASE insulin
amphetamines
indirect acting adrenergic receptor agonists releaser displace NE from mobile pool (neurojunction) psychostimulant do to central release of DA, NE, 5HT Tx. methyl phenidate in narcolepsy and ADHD
Alpha receptor antagonist
decrease TPR, mean BP potential reflex tachycardia, salt/water retention tx. HT, pheochromocytoma, BPH phentolamine, phenoxybenzamine prazosin, doxazosin, terazosin, tamsulosin yohimbine, mirtazapine
atenolol
Beta 1 selective receptor antagonists
TX. angina, HTN, post-MI
adv. Blood lipids increases LDL and TGs, sexual dysfunction, cardiovascular depression. Caution (but safer) in asthma, vasospastic disorders, diabetics (decreases insulin secretion), pregnancy
No sedation
Baroreceptor reflex
Increased BP elicits baroreceptor discharge to cardiovascular center. Nn blockers to block reflex at ganglionic synapse Nm2 block reflex bradycardia HR (vagal tone) B1 block reflex tachycardia HR, contractile force and vasoconstriction.
Beta agonist effects on HR and BP
beta 1: SA node positive chronotropy AV node positive dromotropy atrial/ventricular muscle positive inotropy His-purkinje positive dromotrophy beta 2: blood vessel vasodilate (non-innervated) beta 2 decrease BP (decrease TPR) beta 1 increase HR (increase SV, CO, pulse pressure= systolic-diastolic) isoproterenol, dobutamine salmeterol, albuterol, terbutaline, ritodrine
Beta receptor antagonists
Beta 1 blockade: decreased HR, SV, CO, renin, aqueous humour production beta 2 blockade: may precipitate bronchospasm, vasospasm block glycogenolysism gluconeogenesis increase LDL and TGs Chronic use leads to receptor upregulation; therefor important to taper use to avoid rebound of endogenous amines. acebutolol, atenolol, metoprolol, pindolol, propranolol, timolol labetalol, carvedilol, sotalol
Beta1 receptor activation effects
Gs (increase adenylyl cyclase, cAMP) SA node positive chronotropy AV node positive dromotropy atrial/ventricular muscle positive inotropy His-purkinje positive dromotrophy kidney increased renin
Beta2 receptor activation effects
Gs (increase adenylyl cyclase, cAMP) mostly non-innervated blood vessels vasodilate uterus relaxation brochioles dilation skeletal glycogenolysis (tremor) liver glycogenolysis pancrease increase insulin (metabolize fat and gluconeogenesis)
carvedilol
combined alpha 1 and beta blocker
tx. CHF
Catechol-O-methyltransferase (COMT)
degrades NE at synapse
Clonidine
alpha 2 agonists
- decreases CNS SANS prejunctional outflow of NE
- decrese TPR and HR
TX. mild to moderate HTN and opiate withdrawl
ADV. CNS depression, edema.
DI: TCAs decrease antiHTN effets
Cocaine
indirect acting adrenergic receptor agonists reuptake inhibitor NE (neurojunction)
Closed Angle Glaucoma
Acute or Chronic increased introccular pressure due to blockage of cannal of schlemm Tx. SURGERY. cholinomimetics, carbonic anhydrase inhibitors, mannitol. C/I alpha 1 agonist (myadriasis further closing the angle cannal)
dobutamine
B1>B2 agonist
TX. CHF
Dopamine
sympathomimetic. vasodilate renal, mesenteric, coronary vascular beds
Synthesized from Tyr hydroxylase metabolite: homovanillic acid
- Dopamine will stimulate D1(Gs) at low dose,
- beta 1 at medium dose alpha 1 at high dose
TX. CHF
doxazosin
Alpha 1 selective receptor antagonist
- decrease arteriolar, venous, sphincter resistance
TX. HTN, BPH (decrease urinary frequency and nocturia) [good effect on lipid profil]
ADV reflex tachycardia, first dose effect, orthostatic hypotension, urinary incontenence.