Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCB338

Poster Communications

Angiotensin II effect on dynamics of leukocyte's subpopulations in rats on short-term high salt diet

N. Kolobarić1, M. Mihalj1, A. Matic1, Z. Mihaljevic1, I. Drenjancevic1

1. Department of Physiology and Immunology, Faculty of Medicine, Osijek, Croatia.

AIM: In previous studies, we have demonstrated that short-term high-salt diet affects microcirculation and impairs flow-induced dilation in cerebral vessels and skin microcirculation via increased oxidative stress, in animal models (1) and in humans (2). Present study aimed to determine the effect of subpressor doses of angiotensin II administration via miniosmotic pumps on activated monocytes', granulocytes' and T-lymphocytes' expression levels in rats fed high salt diet (4% NaCl). MATERIALS AND METHODS: Healthy male Sprague-Dawley rats (age of 10-12 weeks), were divided in three groups (n=6/per group; 7-day protocol): 1) LS group - control group fed low salt diet (0,4% NaCl); 2) HS group - fed high salt diet (4% NaCl); 3) HS+ANG II group - fed high salt diet (4% NaCl), on the 5th day of protocol 100 ng of angiotensin II/ kg/ min was administered by Alzet miniosmotic pumps for 3 consecutive days, till the end of protocol. Rats were anaesthetized (IP) with ketamine (75 mg/kg) and midazolam (2.5 mg/kg). Arterial blood was collected on the 8th day and used for flow cytometry measurements of cell adhesion molecules CD11a/LFA-1 and CD11b/Mac-1 as the ligands for ICAM-1, and CD49d/VLA-4 as the ligand for VCAM-1 on subpopulations of leukocytes (BD FACS Canto II flow cytometer; Flowlogic v7.2.1 software). Statistical analyses were performed with Sigma Plot v12.0 and GraphPad Prism v6.01 software. To test differences among groups One-way ANOVA was used; p<0.05 was considered significant. All experimental procedures conformed to the European Guidelines for the Care and Use of Laboratory Animals (directive 86/609) and were approved by the local and national Ethical Committee (Class: UP/I-322-01/14-01/36, No. 525-10/0255-15-6). RESULTS: Expression of CD49d on monocytes was significantly higher in HS group compared to HS+ANG II and LS groups (p=0.04 and p=0.016, respectively). CD49d expression on granulocytes was significantly lower in HS group compared to LS group (p=0.041). CD49d expression on CD8 lymphocytes was lower in HS+ANG II group compared to HS and LS groups (p=0.0204). Granulocytes CD11b expression was significantly higher in HS+ANG II group compared to LS group (p=0.0161). CD11a expression of CD8 lymphocytes was significantly higher in HS group compared to LS and HS+ANG II groups (p=0.027 and p=0.005 respectively). CONCLUSION: Decrease in angiotensin II levels caused by high salt dietary intake may be related to altered immunoreactivity of rats on HS diet. HS leads to a significant increase of CD49d expression on monocytes and CD11a expression on CD8 lymphocytes, potentially increasing their ability to adhere to endothelium. Angiotensin II infusion reversed their expression levels to the values comparable to the LS group, restoring normal immunophenotype.

Where applicable, experiments conform with Society ethical requirements