Stroke Volume

Contractility

Contractility (and SV) increase with:

Catecholamine stimulation via β1 receptor:

• Ca2+ channels phosphorylated --> increases Ca2+ entry --> increases Ca2+-induced Ca2+ release and increased Ca2+ storage in sarcoplasmic reticulum
• Phospholamban phosphorylation --> active Ca2+ ATPase --> increased Ca2+ storage in sarcoplasmic reticulum

Pressure-Volume Cycle

Nitroprusside is a short-acting balanced venous and arterial vasodilator that decreases both preload and afterload. Since these changes are balanced, stroke volume is maintained.