The Influence of Arterial Baroreceptors in Man on the Variability of Blood Pressure and Plasma Catecholamines in Man

¹ Field Marshal Alexander Professor of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Headington, Oxford, England

The variability of intra-arterial blood pressure, recorded over the waking hours in free-ranging subjects away from the hospital, was expressed as the SD of the mean of all recorded beats.

This variability was found to be related to age, the individual's level of arterial pressure, and his baroreflex sensitivity using the Oxford phenylephrine method.

Multiple regression analysis showed that baroreflex sensitivity was the only independent influence on variability. Baroreflex sensitivity also strongly determined the level of pressure rise in response to a number of different stimuli, including bicycling exercise, isometric exercise, mental arithmetic, a reaction time test, and the response to injected phenylephrine or noradrenaline.

Plasma noradrenaline proved a poor index of sympathetic nervous activity, except with bicycle exercise.