Urinary expression of beta-2 microglobulin and osteopontin increases in salt-induced hypertensive rats

Abstracts / Journal of the American Society of Hypertension 10(4S) (2016) e56–e73 were performed. All were analyzed with a computer image analysis system. Results: 1.SEM showed the endothelial cover of the examined vessels from normal animals was smooth and flat and the cell margins were legible, the cells were oriented in the direction of the blood flow and the cells were mainly rhomboidal, oval and drop shaped. In AS animals,outside the areas of plaques the situation of endothelial surface differed from normal animals, on the surface of the aorta single plaques varied greatly in shape and size were present.(Figure 1) The plaques had uneven surfaces, which were covered with endothelial cells integritlly. The de-endothelialization can not be found in the examined vessels. 2.In control group, the aortic intimal stained by HE was smooth and non-thickening. There was no lipid in the subendothelium. In AS group, the aortic intima was significantly thicker and contained lipid plaque. A large number of foam cells could be found in the plaque. The lumen was significantly stenosis. 3.There is a ascending trend of Cx37 expression on vessel smooth muscle cells layer( in AS group(P>0.05), especially in 4 to 8 weekes with high-fat diet. The same trend of cx37 in control group can not be seen. 4.Cx40 expressed invariable in vessel smooth muscle cells of both groups. 5.Cx43 could be detected in none of all groups. Conclusion: The connexin 37 participated in the process of atherosclerosis of ApoE deficient mice. Keywords: Atherosclerosis; Connexins

KIDNEY AND HYPERTENSION P-101 Urinary expression of beta-2 microglobulin and osteopontin increases in salt-induced hypertensive rats Danita Eatman, Muna Elhassey, Vivian Okirie, Nerimiah Emmett, Mohamed Bayorh. Morehouse School of Medicine, Atlanta, GA, United States Introduction: Excessive salt intake is a risk factor for cardiovascular diseases and hypertension associated end-organ damage particularly in African Americans. With the high prevalence of chronic kidney diseases and its consequences, detecting kidney damage at early stages using noninvasive means such as urine markers represents a major opportunity to prevent and/or halt salt-induced renal injury. Several biomarkers have been identified as indicators for different kidney diseases such as glomerulonephritis and interstitial nephritis. Selected proteins, beta-2 microglobulin (B2M) and osteopontin (OPN), were chosen for extensive analysis in the Dahl rodent model based on their association with renal dysfunction, inflammation, and essential hypertension. In this study, we examined the usefulness of B2M and OPN urinary biomarkers for assessing the progression of salt-induced renal injury. Methods: Systolic blood pressure and urinary outflow were measured weekly in the Dahl salt-sensitive rats being fed either a low (0.3% NaCl; LS) or high (8% NaCl; HS) salt diet for four weeks. The Brown Norway rats (SS-13BN) served as the control group. Structural damage to the kidney (tubules or glomeruli) was analyzed using histology, immunohistochemistry, and western blot analysis. Additionally, alterations in renal function were evaluated by comparing serum blood urea nitrogen (BUN), urinary albumin, and biomarkers B2M and OPN to the control group. Results: Over the 4 week treatment period, blood pressure increased by 40% when compared to baseline readings. Urine outflow was 2.5X higher in the Dahl rats fed a high salt diet when compared to control group on the same diet. The urinary levels of B2M increased from 4.9
0.7 (baseline) to 23
4 mg/ml (at week 4) in Dahl SS rats fed a HS diet. Furthermore, B2M levels were 5X higher than OPN levels in the control group; whereas OPN was 3X higher than B2M in the Dahl

e59

SS rats. Microscopic changes (glomerular, tubular, and interstitial) observed in the kidneys of SS-13BN rats on high salt diet resembled those changes observed in SS rats on high salt diet but were less frequent and with lower severity. Conclusion: Together these findings suggest a relationship between renal changes and urinary levels of B2M and/or OPN. Thus, these urinary proteins may serve as potential early indicators of salt-induced renal damage. This work supported by NIH/NIGMS 506 GM08248; NCRR 5P20RR11104. Keywords: Urinary biomarkers; Urinary proteins; Salt-induced hypertension; Renal damage

PRECLINICAL MODELS/EXPERIMENTAL HYPERTENSION P-102 Association of blood pressure and na-pump inhibitor marinobufagenin (MBG) with brain structure, assessed by in vivo MRI in Sprague-Dawley and Dahl-S Rats Olga V. Fedorova,2 Mikayla L. Hall,2 Kenneth W. Fishbein,2 Yulia N. Grigovora,2 Mustafa Bouhrara,2 Wen Wei,2 Jeffrey Long,2 Christopher A. Morrell,2 Peter P. Rapp,2 Edward G. Lakatta,2 Richard G. Spencer,1 Alexei Y. Bagrov.2 1National Institute of Aging, NIH, Baltimore, MD, United States; 2National Institute on Aging, NIH, Baltimore, MD, United States Objectives: Dahl Salt-Sensitive rats (DSS) develop hypertension and cardiovascular remodeling on a high salt diet (HS), unlike their ‘‘ancestors’’, Sprague-Dawley rats (SD). Hypertensive response in DSS is accompanied by increased levels of an endogenous Na-pump inhibitor, MBG, a pro-hypertensive and pro-fibrotic factor. In both DSS and SD, we studied (i) underlying differences in brain structure at baseline and (ii) the effect of HS diet on brain structure. Methods: Six-week old SD and DSS rats were given a HS (8% NaCl) or low salt diet (LS; 0.5% NaCl) for 8 weeks; n¼5-6 for each group. Systolic blood pressure (SBP), body weight (BW), 24-hr urinary MBG excretion (uMBG) and brain MRI data were collected at week 8. Results: DSS had lower BW and higher SBP than SD fed similar diets. After 8 weeks on HS, SBP was higher by 82 mmHg in DSS (p<0.01, ANOVA) and by 16 mmHg in SD (ns). uMBG was greater by 15-fold in DSS and 3-fold in SD. uMBG was correlated to SBP in DSS (R¼0.689, P¼0.028) but not in SD (R¼0.278, P¼0.41). Brain and hippocampus volumes were smaller in DSS vs. SD (Table), and ventricle volume, normalized by brain volume, was larger by 1.5-1.8-fold in DSS vs. SD on both diets (P<0.01, ANOVA). Hippocampal ADC_AP, mean diffusivity, and R2’ were higher in DSS vs. SD on LS. HS diet gave higher R2’ in SD, whereas in DSS, R2’ was lower on HS. Hippocampal ADC_AP was negatively correlated with SBP in DSS, and was positively correlated with SBP in SD. Correlations of hippocampal R2’ with SBP and uMBG were negative in DSS, and positive in SD, although the correlation between R2’ and SBP in SD was not significant (Table). Conclusions: Salt-induced hypertension was observed only in DSS, in which SBP was positively associated with uMBG levels. DSS on LS had shorter hippocampal T2* and greater R2’ than SD on LS, which may indicate the presence of microvascular disease in DSS even without HS intake. The effect of HS on these parameters was opposite in DSS and SD. This may indicate a compensatory mechanism in DSS, which can affect brain microcirculation. Elevated BP may increase brain blood supply and improve the structure of the hippocampus. MBG is a pro-fibrotic factor, and its participation in changes in brain microvasculature, brain structures and possibly in cognitive functions in salt-sensitive hypertension merits future investigations. Keywords: Salt-sensitivity; Cardiotonic steroid marinobufagenin; Blood pressure; Brain MRI