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Low-dose ouabain constricts small arteries from ouabain-hypertensive rats: implications for sustained elevation of vascular resistance.

ABSTRACT: Prolonged ouabain administration to normal rats causes sustained blood pressure (BP) elevation. This ouabain-induced hypertension (OH) has been attributed, in part, to the narrowing of third-order resistance arteries (approximately 320 microm internal diameter) as a result of collagen deposition in the artery media. Here we describe the structural and functional properties of fourth-order mesenteric small arteries from control and OH rats, including the effect of low-dose ouabain on myogenic tone in these arteries. Systolic BP in OH rats was 138 +/- 3 versus 124 +/- 4 mmHg in controls (P < 0.01). Pressurized (70 mmHg) control and OH arteries, with only a single layer of myocytes, both had approximately 165-microm internal diameters and approximately 20-microm wall thicknesses. Even after fixation, despite vasoconstriction, the diameters and wall thicknesses did not differ between control and OH fourth-order arteries, whereas in third-order arteries, both parameters were significantly smaller in OH than in controls. Myogenic reactivity was significantly augmented in OH fourth-order arteries. Nevertheless, phenylephrine- (1 microM) and high K(+)-induced vasoconstrictions and acetylcholine-induced vasodilation were comparable in control and OH arteries. Vasoconstrictions induced by 5 microM phenylephrine and by 10 mM caffeine in Ca(2+)-free media indicated that releasable sarcoplasmic reticulum Ca(2+) stores were normal in OH arteries. Importantly, 100 nM ouabain constricted both control and OH arteries by approximately 26 microm, indicating that this response was not downregulated in OH rats. This maximal ouabain-induced constriction corresponds to a approximately 90% increase in resistance to flow in these small arteries; thus ouabain at EC(50) of approximately 0.66 nM should raise resistance by approximately 35%. We conclude that dynamic constriction in response to circulating nanomolar ouabain in small arteries likely makes a major contribution to the increased vascular tone and BP in OH rats.

SUBMITTER: Zhang J

PROVIDER: S-EPMC2755988 | biostudies-literature |

REPOSITORIES: biostudies-literature

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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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Low-dose ouabain constricts small arteries from ouabain-hypertensive rats: implications for sustained elevation of vascular resistance.

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