Canonical Question
Antihypertensive
Master answer
Adrenoceptor Effects
| Organ / Tissue | α1 (A, B, D) | α2 (A, B, C) | β1 | β2 | |
|---|---|---|---|---|---|
| Nervous System | CNS | ↑ locomotor activity, neurotransmission | Sedation inhibition of sympathetic flow neurotransmission | ||
| eye | iris Sm.M contracts (pupils dilate) | relaxation of ciliary muscle for far vision | |||
| Sympathetic nerve terminal | inhibit Noradrenaline release | ↑ neurotransmitter release | |||
| Cholinergic neurons and cell bodies of noradrenergic neurons | Inhibition of firing | ||||
| CVS | Myocardium | ↑ force of contraction | SA node: ↑HR Atria: ↑contractility, ↑conduction velocity A-V node, HIS, Purkinge: ↑automaticity, cond vel Ventricles: ↑contractility, conduction, velocity, automaticity, and rade of idioventriculatr pacemakers | similar effect to β1 | |
| Vascular Smooth muscle | contraction | contraction | relax | ||
| Endothelium | release of vasodilator substance | ||||
| SKELETAL MUSCLE | ↑ contractility, glycogenolysis, K+ uptake | ||||
| Smooth Muscle | GIT | relaxation | relax | ||
| sphincters (GI, bladder) | contract | relax | |||
| uterus | contract | relax | |||
| Respiratory | bronchial glands | ↓ secretion | ↑ secretion | ||
| Airway | bronchodilation | ||||
| Haem | Platelets | Aggregation granule release | |||
| GIT | Salivary gland | secretion (K+, H2O) | Amylase secretion | ||
| Jejunum | Inhibition of secretion | ||||
| Liver | Glycogenolysis, gluconeogenesis, ureogenesis | Glycogenolysis, Gluconeogenesis | |||
| motility and tone | decreased stomach, intestine | decreased | decreased | decreased | |
| Pancreas | ↓ secretion | Inhibition of insulin release | Insulin secretion | ||
| splenic capsule | contracts | relaxation | |||
| Kidney | Glucogenesis (proximal tubule) ↑ renin secretion | Inhibition of renin release | ↑ Renin secretion | ||
| Metabolic / Endocrine | Adipose tissue | Glycogenolysis | Inhibition of lipolysis | Lipolysis | |
| Posterior pituitary | ADH secretion | ||||
| Others | Eye | lacrimation | ↓ intra ocular pressure | ||
| Melanocytes | Inhibition of MSH-induced granule dispersion | ||||
β3 effects:
- Fat
- lipolysis and thermogenesis
Metoprolol Pharmacology
Exam appearances
| Exam | Exact wording | Relationship | Success |
|---|---|---|---|
| 2023B Q12 | List the effects of stimulation of adrenoreceptors on target organs and tissues (60% marks). Describe the mechanism of action and pharmacokinetics of metoprolol (40% marks). | historical_member | — |