Sympathetic Nervous System

Adrenergic Receptors do what?

Mediate effects in the SNS

ALL are g protein coupled receptors

What are the Adrenoreceptor subtypes?

Alpha (1a 1b 1d and 2) and Beta (1 2 and 3)

Is receptor selectivity absolute?

No

What is the term for nearly absolute receptor selectivity?

Termed specificity

Selectivity refers to

a drugs ability to preferentially activate one subgroup of receptors at conc. that have little to no effect on other subtypes

Clinical effects of drugs determined by

Selectivity for that receptor and expression of receptors in a given tissue

Alpha 1 includes what pathway

Gq protein coupled - IP3→ DAG

Alpha 1 leads to

vasoconstriction

Contraction of GI (ejaculation)

Secretion of sweat

RELAXATION OF GUT

What is the selective agonist and antagonist for a1?

Agonist: Phenylephrine

Antagonist: Prazosin

What is the pathway of a2?

Gi/Go coupled receptor - Gi → AC-cAMP

What does the a2 pathway do?

Inhibits transmitter release

Decreased symp flow

Decrease insulin release

Aggregation of platelets

vasoconstriction

What are the selective agonist/antagonist of a2?

Agonist: Clonidine

Antagonist: Yohimbine

What is the pathway of b1?

Gs - Gs → AC-cAMP

What are the effects of B1?

SA node: increase rhythmically chrono therapy

AV node: Increase velocity

Ventricles: Increase contractility

Kidney: Increased renin release

What are the B1 selective agonists/antagonist?

Agonist: Dobutamine

Antagonist: Atenolol, metoprolol, bisoprolol

What is the pathway of B2?

Gs - Gs → AC-cAMP

Found in smooth muscles of many organs and causes relaxation

What are the effects of B2?

bronchodilation

Vasodilate

Uterine relaxation

Gut relaxation

Glucagon secretion

Detrusor muscle relaxation

Increase aqueous secretion in eye

What are the B2 selective agonist/antagonist?

Agonist: Albuterol

Antagonist: Butaxamine

What is the b3 pathway?

Gs - Gs → AC-cAMP

What are the effects of B3?

Adipose tissue

Detrusor muscle relaxation

What is the selective agonist of B3?

Mirabegon