Plasma norepinephrine variations correlate with peripheral vascular resistance in resting humans

Shifts in sympathetic nervous activity to resistance blood vessels are reflected in spontaneous oscillations in plasma norpinephrine (NE) levels. Plasma NE correlated negatively with cardiac output and positively with total peripheral resistance. The negligible cardiac NE spillover into plasma and the inverse link between total peripheral resistance and cardiac output are probably responsible for the negative correlation between plasma NE levels and cardiac output.