Published online before print October 10, 2005, doi: 10.1161/01.HYP.0000187014.92384.a4
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(Hypertension. 2005;46:1095.)
© 2005 American Heart Association, Inc.
Editorial Commentaries |
Baroreflexes in Hypertension
A Mystery Revisited
From the Institute of Physiology, Humboldt University, Berlin, Germany
Correspondence to Dr Pontus B. Persson, Institut für Vegetative Physiologie, Charité Universitätsmedizin Berlin, Tucholskystr. 2, D-10117 Berlin. E-mailpontus.persson@charite.de
An extract of the first 250 words of the full text is provided, because this article has no abstract. |
To date, most studies investigating baroreflexes in hypertension have been performed either by recording baroreflex afferents or by denervating them. In the current issue of Hypertension, Lohmeier et al1 present data on the effects of chronic carotid sinus stimulation (CSS) in hypertensive animals. Striking differences were observed during CSS in dogs with angiotensin II (Ang II)-induced hypertension as compared with control conditions. In line with a previous study,2 baroreflex activation by CSS significantly reduced blood pressure during control. In contrast, the hypotensive effect was markedly attenuated in Ang II hypertensive dogs. This observation fits very well with today’s understanding of baroreflexes in several forms of hypertension.
Remarkably, it is still not fully understood how the autonomic nervous system acts in hypertension, although the issue dates back to the very beginnings of research on cardiovascular reflexes. During that era, it was generally held that baroreflexes continuously buffer sympathetic nervous output. Thus, dissection of the afferent nerves supplying regions of the baroreceptors (carotid sinuses and aortic arch) was thought to increase long-term blood pressure. Koch described what he termed Entzügelungshochdruck (disinhibitory hypertension) in many species.3 Today, neurogenic hypertension is commonly used to describe hypertension following denervation of baroreceptors. The concept of neurogenic hypertension was never seriously questioned until the 1970s when Cowley et al performed long-term studies in conscious dogs. In these experiments, only slight increases in blood pressure were found after baroreceptor denervation. Neurogenic hypertension mainly seems to be observed under special experimental conditions: either in animals that are not
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