Rat Blood Pressure DEMO

Noradrenaline is the main sympathetic transmitter at most neuronal sites. Heart rate and force are increased through beta₁ -adrenoceptors (G-protein coupled to adenylate cyclase). Beta₂ -adrenoceptors are little affected therefore arteriolar dilatation is not seen and diastolic pressure does not fall. Alpha₁ -adrenoceptors in e.g. skin and gut cause constriction of vessels which increases total peripheral resistance and systolic pressure is increased.