Analbuminemic Nagase Rats: Blood Pressure Response to Dietary Salt Challenge

Abstract

Background: The role of albumin on blood pressure response to different salt challenges is not known. Therefore, we studied the blood pressure response of analbuminemic Nagase rats (NAR) to different salt challenges. 11β-Hydroxysteroid dehydrogenase type 2 (11β-HSD2), the enzyme regulating the glucocorticoid access to the mineralocorticoid receptor, an enzyme that is decreased in humans with salt sensitive hypertension and other diseases with abnormal renal salt retention, was assessed during salt challenges. Methods: Blood pressure was measured continuously by an intra-arterial catheter and a telemetry system in NAR (n = 8). NAR were set successively for 7 days on a normal (0.45% NaCl), high (8% NaCl), low (0.1% NaCl) and normal salt diet again, to assess salt related response in mean systolic (SBP) and diastolic blood pressure (DBP). 11β-HSD2activity was assessed by measuring the urinary (THB + 5α-THB)/THA ratio with gas chromatography – mass spectrometry. Results: Mean SBP and DBP increased with high salt intake (normal salt vs. high salt: SBP: 114 ± 1 vs.119 ± 3 mm Hg, p < 0.01; DBP: 84 ± 1 vs. 88 ± 3 mm Hg; n = 8; p < 0.01). Urinary (THB +5α-THB)/THA ratio increased during the high-salt period when compared to the normal-salt period (high salt vs. normal salt: 0.52 ± 0.10 vs. 0.37 ± 0.07; p = 0.05) indicating decreased 11β-HSD2activity. Conclusion: Analbuminemic Nagase rats express increased blood pressure and reduced 11β-HSD2 activity in response to a high-salt diet.