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High salt (HNa+) intake increases blood pressure (BP) and renal sympathetic nerve activity (RSNA) to angiotensin II (ANGII) intracerebroventricle (ICV) infusion
Author(s) -
Houghton Belinda Lee,
Huang Chunlong,
Johns Edward J
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a753-a
Subject(s) - medicine , cannula , blood pressure , angiotensin ii , endocrinology , saline , femoral artery , anesthesia , surgery
Previous works suggest a causal link between dietary salt intake, brain ANGII, and RSNA control of blood pressure. Salt intake at a young age may alter central AT1 receptors and the autonomic response to changes in central ANGII. This study investigated how HNa + intake from 4 weeks of age influenced BP and RSNA after low dose ANGII ICV infusion. Male Wistar rats (con, n=7; 6 weeks HNa + diet, n=5) were anaesthetized. A guide cannula was placed into the right lateral ICV. Cannulae were inserted into the femoral artery and vein for BP measurement and saline infusion. The left kidney was exposed and recording electrodes sealed onto a renal nerve. ANGII ICV (25ng/μL, 1 μL/min) was infused for 2 min. BP and RSNA were averaged prior and post ICV infusion. Means ±SEM were subjected to one way ANOVA. Linear regression analysis compared %ΔRSNA versus %ΔBP at 30 min post ICV infusion. P<0.05 indicated significance. Baseline BP was not different between groups (con: 92.9±3.5mmHg; HNa + : 89.3±3.4mmHg). ANGII ICV increased BP in the HNa + rats 5 min post infusion (con ΔBP: 1.3±0.4 mmHg, P=0.059; HNa + ΔBP: 15.9±2.8 mmHg, P<0.05). 30 min post infusion, BP was higher than baseline in both groups (con ΔBP: 1.4±0.4 mmHg, P<0.05; HNa + ΔBP: 5.5±0.4mmHg, P<0.05). There was a positive linear relationship between % ΔRSNA versus % ΔBP in the HNa + group (r 2 =0.84, P<0.05), but not in the control group (r 2 =0.008, P=0.84). These results suggest that chronic HNa + intake augments the sensitivity of the BP and RSNA response to low dose ANGII ICV. This project was supported by HRB RP/2004/17.