Low Response of Renin-Angiotensin System to Sodium Intake Intervention in Chinese Hypertensive Patients

The captopril challenge test for diagnosing primary Aldosteronism in a Chinese population

BACKGROUND

The Captopril challenge test (CCT) is an easy-conduct confirmatory test for diagnosing primary aldosteronism (PA). Guidelines show that plasma aldosterone is normally suppressed by captopril (> 30%) in primary hypertension (PH) and in healthy people. It is unclear whether this standard is applicable in Chinese subjects. The aim of the present study was to investigate the post-CCT efficacy of plasma aldosterone concentration (PAC) suppression and determine the post-CCT aldosterone renin activity ratio (ARR) and PAC for PA diagnosis.

METHODS

We recruited 110 consecutive patients with PA, 163 with primary hypertension (PH), and 40 healthy volunteers (NC). The CCT was conducted in all patients. Total sodium intake was estimated from 24-h urinary excretions. ROC curves were used to analyze the efficiency of different CCT diagnostic criteria for diagnosing PA.

RESULTS

In NC and PH patients, PRA was increased and PAC was decreased post-CCT (P < 0.05). The mean degree of PAC decline after CCT was approximately 9.3%, and only 11.7% of the patients with PH showed a greater than 30% suppression of PAC after CCT. In patients with PA, the post-CCT change in PRA and PRC was slight. The post-CCT degree of PAC decline was unrelated to dietary salt intake. The areas under the ROC for the post-CCT ARR, PAC and PAC suppression % were 0.994, 0.754 and 0.606, respectively. The optimal post-CCT cutoff value for ARR for diagnosing PA was 20, which yielded a sensitivity and specificity of 94.0 and 99.4%, respectively.

CONCLUSIONS

The PAC suppression percentage after CCT recommended by current clinical guidelines is not applicable when diagnosing Chinese subjects with PA. Compared to post-CCT PAC, post-CCT ARR was a better approach, having an optimal cutoff of 20 when interpreting the results of the CCT in Chinese patients. We found no relationship between high salt intake and low responses of the renin-angiotensin system (RAS) to the CCT.

Early administration of empagliflozin preserved heart function in cardiorenal syndrome in rat

This study tested the hypothesis that early administration of empagliflozin (Empa), an inhibitor of glucose recycling in renal tubules, could preserve heart function in cardiorenal syndrome (CRS) in rat. Chronic kidney disease (CKD) was caused by 5/6 subtotal nephrectomy and dilated cardiomyopathy (DCM) by doxorubicin (DOX) treatment. In vitro results showed that protein expressions of cleaved-caspase3 and autophagy activity at 24 h/48 h in NRK-52P cells were significantly upregulated by para-Creso treatment; these were significantly downregulated by Empa treatment. Flow cytometric analysis showed that annexin-V (i.e., early/late apoptosis) in NRK-52P cells expressed an identical pattern to cleaved-caspase3 between the two groups (all p < 0.001). Adult-male-SD rats (n = 18) were equally categorized into group 1 (sham-control), group 2 (CRS) and group 3 [CRS + Empa; 20 mg/kg/day]. By day-42 after CRS induction, left-ventricular ejection fraction (LVEF) level exhibited an opposite pattern, whereas LV end-diastolic dimension and creatinine level displayed the same pattern, to cleaved-caspase3 among the three groups (all p < 0.0001). In LV tissues, protein expressions of inflammatory (tumor-necrosis factor-α/nuclear-factor-κB/interleukin-1ß/matrix-metalloprotianse-9), oxidative stress (NOX-1/NOX-2/oxidized protein), apoptotic (mitochondrial-Bax/cleaved-caspase-3/cleaved-PARP), fibrotic (transforming-growth factor-ß/Smad3), DNA/mitochondrial-damage (γ-H2AX/cytosolic-cytochrome-C) and heart failure (brain natriuretic peptide (BNP) levels displayed an opposite pattern to LVEF among the three groups (all p < 0.0001). Additionally, cellular expressions of DNA-damage/heart-failure (γ-H2AX+//XRCC1+CD90+//BNP+) biomarkers and histopathological findings of fibrotic/condensed collagen-deposition areas and apoptotic nuclei showed an identical pattern, whereas connexin43 and small-vessel number exhibited an opposite pattern, to inflammation among the three groups (all p < 0.0001). In conclusion, Empa therapy protected heart and kidney against CRS injury.