Baroreflex sensitivity in secondary hypertension.

A deranged baroreceptor control of the cardiovascular functions has been reported in essential hypertension. Studies performed in experimental animals and in humans using different approaches have documented an impairment of both baroreflex heart rate modulation (resetting and loss of sensitivity) and baroreceptor control of peripheral vasomotor tone (only resetting). Baroreflex alterations have been reported also in secondary forms of hypertension, but data are controversial. This paper reviews recent works concerning baroreflex function in secondary hypertension. Either structural changes of arterial wall (decrease of vascular distensibility) or functional processes (involving angiotensin II, aldosterone, catecholamines, nitric oxide) have been proposed as potential mechanisms responsible for baroreflex readjustments in secondary hypertension. It remains unclear, and it is difficult to define exactly, if baroreflex changes associated with secondary form of hypertension are primarily due to factors specific for different hypertensive conditions, or merely follow blood pressure elevation.