Pharmacology B

affectting Heart Rate

effecting Contractility

affecting Cardiac Impulse Conduction Velocity

• Preload
• Afterload
• Contractility
• Heart rate
• Cardiac Output= The amount of blood pumped by the L ventricle each minute.
• CO= SV x HR
• - meaning SV and HR are inversley related.

Ventricular filling pressure vs Systemic vascular resistance

• a) < 120/ <80
• b) 120-139/ 80-90
• c) 140/159/ 90-99
• d) > 160/ >100

systolic/diastolic

• Sympathetic nervous system
• - inc HR directly via Beta-receptor stimulation
• The kidneys
• - controls blood volume via water reabsorbtion
• (volume is proportional to Bp)
• Systemic/peripheral vascular resistance
• -vasoconstriction via alpha-receptor stimulation
• =inc resistance= HR

• Diuretics
• Sympatholytics
• Angiotensin Inhibitors
• Vasodilators

• Thiazide diuretics
• Loop Diuretics: most potent
• K⁺ sparing diuretics: prevent hypokalemia, used with thiazides

Cause and increase in renal Na+ excretion (natriuresis)= increased water excretion. This decreases blood volume and thus, decreases CO (and SVR)

Diuril (Chlorothiazide)

Moderate natriuretic effect. Can cause hypokalemia

alpha 1 antagonists: cause vasodilation, reduce SVR. Can result in reflex CV stimulation or kidney reabsorbtion (renin-angioT-aldos system)

Beta antagonists/blockers: block receptors on the heart and juxtaglomerular cells= dec HR and blood volume.