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Critical blood pressure threshold dependence of hypertensive injury and repair in a malignant nephrosclerosis model.

ABSTRACT: Most patients with essential hypertension do not exhibit substantial renal damage. Renal autoregulation by preventing glomerular transmission of systemic pressures has been postulated to mediate this resistance. Conversely, malignant nephrosclerosis (MN) has been postulated to develop when severe hypertension exceeds a critical ceiling. If the concept is valid, even modest blood pressure (BP) reductions to below this threshold regardless of antihypertensive class (1) should prevent MN and (2) lead to the healing of the already developed MN lesions. Both predicates were tested using BP radiotelemetry in the stroke-prone spontaneously hypertensive rats receiving 1% NaCl as drinking fluid for 4 weeks. Severe hypertension (final 2 weeks average systolic BP, >200 mm Hg) and MN (histological damage score 36±5; n=27) developed in the untreated stroke-prone spontaneously hypertensive rats but were prevented by all antihypertensive classes (enalapril [n=15], amlodipine [n=13], or a hydralazine/hydrochlorothiazide combination [n=15]) if the final 2-week systolic BP remained <190 mm Hg. More impressively, modest systolic BP reductions to 160 to 180 mm Hg (hydralazine/hydrochlorothiazide regimen) initiated at ?4 weeks in additional untreated rats after MN had already developed (injury score 35±4 in the right kidney removed before therapy) led to a striking resolution of the vascular and glomerular MN injury over 2 to 3 weeks (post-therapy left kidney injury score 9±2, P<0.0001; n=27). Proteinuria also declined rapidly from 122±9.5 mg/24 hours before therapy to 20.5±3.6 mg 1 week later. These data clearly demonstrate the barotrauma-mediated pathogenesis of MN and the striking capacity for spontaneous and rapid repair of hypertensive kidney damage if new injury is prevented.

SUBMITTER: Griffin KA

PROVIDER: S-EPMC4162752 | biostudies-literature | 2014 Oct

REPOSITORIES: biostudies-literature

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Critical blood pressure threshold dependence of hypertensive injury and repair in a malignant nephrosclerosis model.

Griffin Karen A KA Polichnowski Aaron A Litbarg Natalia N Picken Maria M Venkatachalam Manjeri A MA Bidani Anil K AK

Hypertension (Dallas, Tex. : 1979) 20140623 4

Most patients with essential hypertension do not exhibit substantial renal damage. Renal autoregulation by preventing glomerular transmission of systemic pressures has been postulated to mediate this resistance. Conversely, malignant nephrosclerosis (MN) has been postulated to develop when severe hypertension exceeds a critical ceiling. If the concept is valid, even modest blood pressure (BP) reductions to below this threshold regardless of antihypertensive class (1) should prevent MN and (2) le ...[more]

PMID: 24958497

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Project description:Current prehospital traumatic brain injury guidelines use a systolic blood pressure threshold of less than 90 mm Hg for treating hypotension for individuals 10 years and older based on studies showing higher mortality when blood pressure drops below this level. However, the guidelines also acknowledge the weakness of the supporting evidence.To evaluate whether any statistically supportable threshold between systolic pressure and mortality emerges from the data a priori, without assuming that a cut point exists.Observational evaluation of a large prehospital database established as a part of the Excellence in Prehospital Injury Care Traumatic Brain Injury Study. Patients from the preimplementation cohort (January 2007 to March 2014) 10 years and older with moderate or severe traumatic brain injury (Barell Matrix Type 1 classification, International Classification of Diseases, Ninth Revision head region severity score of 3 or greater, and/or Abbreviated Injury Scale head-region severity score of 3 or greater) and a prehospital systolic pressure between 40 and 119 mm Hg were included. The generalized additive model and logistic regression were used to determine the association between systolic pressure and probability of death, adjusting for significant/important confounders.The main outcome measure was in-hospital mortality.Among the 3844 included patients, 2565 (66.7%) were male, and the median (range) age was 35 (10-99) years. The model revealed a monotonically decreasing association between systolic pressure and adjusted probability of death across the entire range (ie, from 40 to 119 mm Hg). Each 10-point increase of systolic pressure was associated with a decrease in the adjusted odds of death of 18.8% (adjusted odds ratio, 0.812; 95% CI, 0.748-0.883). Thus, the adjusted odds of mortality increased as much for a drop from 110 to 100 mm Hg as for a drop from 90 to 80 mm Hg, and so on throughout the range.We found a linear association between lowest prehospital systolic blood pressure and severity-adjusted probability of mortality across an exceptionally wide range. There is no identifiable threshold or inflection point between 40 and 119 mm Hg. Thus, in patients with traumatic brain injury, the concept that 90 mm Hg represents a unique or important physiological cut point may be wrong. Furthermore, clinically meaningful hypotension may not be as low as current guidelines suggest. Randomized trials evaluating treatment levels significantly above 90 mm Hg are needed.

Project description:Background: The vascular wall of small arteries is heavily affected by high blood pressure. However, the underlying mechanisms causing vascular changes are not fully elucidated. Using a novel data-independent acquisition mass spectrometry (DIA-MS) approach, we aimed to determine the proteomic changes in small mesenteric arteries during early-onset high blood pressure in a rat model of hypertension. Methods: Snap frozen small mesenteric and renal arteries from the spontaneous hypertension rat (SHR) model and Wistar Kyoto (WKY) control rats were collected from two time points (6- and 12-weels of age) and analyzed by a label free quantitative DIA-MS workflow. Mesenteric arteries from Wister Hannover rats were included as an additional control to clarify genetic drift caused by selective inbreeding. Results: We identified a total of 3956 consistent proteins in the mesenteric artery wall and found that 286 proteins were significantly regulated in 12-weeks old SHRs compared to WKY controls. Comparing to an in silico matrisome database, we identified 38 extracellular matrix-associated proteins that could distinguish SHRs from WKY controls. Furthermore, when comparing the significantly regulated proteins identified in mesenteric and renal arteries, we identified 18 proteins, including Serpina3l, Igg-2a, ENSRNOG00000049829, Acyp2, Enpp3, Lss, Acaa1a, Basp1, an isoform of Basp1, Flot1, Flot2, Gstt1, Nit1, Ppid, Ikbkap, Poglut3, P4ha2 and Usp15, that were changed in both vascular beds. These proteins were associated with vital cellular processes, such as dyslipidemia, protease inhibition, remodeling and generation of reactive oxygen species. Majority of the identified proteins and pathways were associated with hypertension, and mapping the underlying changes help understanding the pathological processes occurring in the arterial wall during early-onset hypertension. Conclusions: Our data provides an in-depth analysis of the proteomic architecture of the mesenteric and renal artery wall from SHRs and WKY control rats. We identified 18 novel candidate proteins that highlights critical changes in small arteries of the SHR.

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Critical blood pressure threshold dependence of hypertensive injury and repair in a malignant nephrosclerosis model.

Publications

Critical blood pressure threshold dependence of hypertensive injury and repair in a malignant nephrosclerosis model.

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