Investigation of the effects of ß-blockers on CVS

Procedure 2 students acts as volunteers PR and Bp recorded for each volunteer Exercise for 5 min. PR and Bp recorded immediately following exercise and after 3 min. One student take 40 mg propranolol, other take placebo Again record resting and exercise PR & Bp

Table of results After treatment 30 min Before treatment 3 min after After exercise rest PR Bp

Propranolol Prototype Drug Trade name (( Inderal )) Non-selective Lipid soluble (cross BBB) Low bioavailability (extensive 1st. P. E.) T1\2 = 3 - 6 hr.

Pharmacological effects Cardiac effects : Negative inotropic effects Negative chronotropic effects. ↓ Cardiac output (COP) and O2 consumption ↓ S-A and A-V conduction velocity All effects are mostly due to β1 blockade & more pronounced during exercise

Pharmacological effects Vascular effects : Prevents β2-mediated vasodilatation Hypotension triggers a reflex peripheral vasoconstriction.

Pharmacological effects Antihypertensive effects : Reduction in COP Reduction of renin release from the juxtaglomerular cells of the kidney Presynaptic inhibition (reducing ND release) TPR

Pharmacological effects Disturbances in glucose metabolism: ↓Glycogenolysis ↓Gluconeogenesis propranolol can cause exercise-induced hypoglycemia propranolol can mask the symptoms of hypoglycemia

Clinical Uses CVS Angina pectoris: ! Myocardial infarction: ! Dysrhythmias :  Heart failure : !! Hypertension : 

Clinical Uses Thyrotoxicosis Migraine prophylaxis Benign essential tremor Anxiety

Adverse effects Bronchoconstriction Bradycardia Arrhythmias. (rebound tachycardia) Cardiac depression Hypoglycemia Fatigue Cold extremities Sexual impairment Nightmares

Contraindications asthma and other bronchospastic conditions, severe bradycardia atrioventricular blockade severe unstable left ventricular failure. Diabetes