Neurogenic hypertension and elevated vertebrobasilar arterial resistance: is there a causative link?
ABSTRACT There is evidence of sympathetic overdrive in a significant proportion of patients with essential hypertension and an animal model of the condition, the spontaneously hypertensive rat (SHR). The reasons for this remain elusive. However, there is also evidence of narrowing of the arteries supplying the brainstem in the SHR and hypertensive humans. In this review, we discuss the possible role of brainstem hypoperfusion in driving increased sympathetic activity and hypertension.
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ABSTRACT: It is widely accepted that the pathophysiology of hypertension involves autonomic nervous system dysfunction, as well as a multitude of immune responses. However, the close interplay of these systems in the development and establishment of high blood pressure and its associated pathophysiology remains elusive and is the subject of extensive investigation. It has been proposed that an imbalance of the neuro-immune systems is a result of an enhancement of the "proinflammatory sympathetic" arm in conjunction with dampening of the "anti-inflammatory parasympathetic" arm of the autonomic nervous system. In addition to the neuronal modulation of the immune system, it is proposed that key inflammatory responses are relayed back to the central nervous system and alter the neuronal communication to the periphery. The overall objective of this review is to critically discuss recent advances in the understanding of autonomic immune modulation, and propose a unifying hypothesis underlying the mechanisms leading to the development and maintenance of hypertension, with particular emphasis on the bone marrow, as it is a crucial meeting point for neural, immune, and vascular networks.Current Hypertension Reports 05/2013; · 3.90 Impact Factor
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ABSTRACT: Background MicroRNAs (miRs), as essential gene expression regulators, modulate cardiovascular development and disease and thus they are emerging as potential biomarkers and therapeutic targets in cardiovascular disease, including hypertension. Methods and Results We assessed the expression levels of the microRNAs miR-9 and miR-126 in 60 patients with untreated essential hypertension and 29 healthy individuals. All patients underwent two-dimensional echocardiography and 24-h ambulatory blood pressure monitoring. MicroRNA expression levels in peripheral blood mononuclear cells were quantified by real-time reverse transcription polymerase chain reaction. Hypertensive patients showed significantly lower miR-9 (9.69±1.56 versus 41.08±6.06, p<0.001) and miR-126 (3.88±0.47 versus 8.96±1.69, p<0.001) expression levels compared with healthy controls. In hypertensive patients, miR-9 expression levels showed a significant positive correlation (r=0.437, p<0.001) with left ventricular mass index. Furthermore, both miR-9 (r=0.312, p=0.015) and miR-126 (r=0.441, p<0.001) expression levels in hypertensive patients showed significant positive correlations with the 24-h mean pulse pressure. Conclusions Our data reveal that miR-9 and miR-126 are closely related to essential hypertension in humans, as they show a distinct expression profile in hypertensive patients relative to healthy individuals and they are associated with clinical prognostic indices of hypertensive target organ damage in hypertensive patients. Thus, they may possibly represent potential biomarkers and candidate therapeutic targets in essential hypertension.Journal of the American Society of Hypertension (JASH) 01/2014;
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ABSTRACT: Despite advances in our understanding concerning the pathology of hypertension, the mechanisms that underpin the origin of hypertension remain to be fully elucidated. This enigma is, at least in part, due to inherent limitations of various animal models of hypertension. Here, we show the genetically modified Cyp1a1-Ren2 rat model, in which the onset and severity of angiotensin II-dependent hypertension can be tightly controlled, as an effective model for investigating increased sympathetic drive for the onset of hypertension. Cyp1a1-Ren2 rats were surgically prepared with radiotelemetric transmitters for the continuous measurement of arterial blood pressure (ABP). ABP was recorded in freely moving rats that were fed with either normal rat chow or a diet containing indole-3-carbinol (0.225 % w/w) for 7 days to induce hypertension. Structural morphology of and endothelial NO synthase (eNOS) protein expression in heart and/or vascular tissue were analyzed. Sympathetic tone was estimated using spectral analysis of heart rate variability. The progressive induction of hypertension over 7 days was matched with a parallel increase in sympathetic tone. By day 7 of hypertension, eNOS expression in the mesenteric artery was elevated. However, the elevated ABP, sympathetic tone, and eNOS had not elicited gross morphological remodeling of the heart or vasculature. Importantly, both the increase in sympathetic tone and overexpression of eNOS within the vasculature were reversed when ABP was returned to normal. We conclude that the Cyp1a1-Ren2 rat provides an effective model for investigating specific adverse and transient changes in central sympathetic modulation of arterial blood pressure during the early onset of angiotensin-dependent hypertension.Pflügers Archiv - European Journal of Physiology 08/2013; · 4.87 Impact Factor