Effects of intravenous bolus injection of nicorandil on renal artery flow velocity assessed by color Doppler ultrasound

The moderate-intensity continuous exercise maintains renal blood flow and does not impair the renal function

Exercise is restricted for individuals with reduced renal function because exercising reduces blood flow to the kidneys. Safe and effective exercise programs for individuals with reduced renal function have not yet been developed. We previously examined the relationship between exercise intensity and renal blood flow (RBF), revealing that moderate-intensity exercise did not reduce RBF. Determining the effects of exercise duration on RBF may have valuable clinical applications. The current study examined the effects of a single bout of continuous exercise at lactate threshold (LT) intensity on renal hemodynamics. Eight adult males participated in this study. Participants underwent 30 min of aerobic exercise at LT intensity using a cycle ergometer. Evaluation of renal hemodynamics was performed before and after exercise, in the recovery phase using ultrasound echo. Furthermore, blood and urine samplings were conducted before and after exercise, in the recovery phase. Compared with resting, RBF was not significantly changed immediately after continuous exercise (319 ± 102 vs. 308 ± 79 ml/min; p = 0.976) and exhibited no significant changes in the recovery phase. Moreover, urinary kidney injury molecule-1 (uKIM-1) level exhibited no significant change immediately after continuous exercise (0.52 ± 0.20 vs. 0.46 ± 0.27 μg/g creatinine; p = 0.447). In addition, the results revealed no significant change in urinary uKIM-1 in 60-min after exercise. Other renal injury biomarkers exhibited a similar pattern. These findings indicate that a single bout of moderate-intensity continuous exercise maintains RBF and does not induce renal injury.

Nicorandil Decreases Renal Injury in Patients With Coronary Heart Disease Complicated With Type I Cardiorenal Syndrome

ABSTRACT

Cardiorenal syndrome (CRS) is a group of disorders in which heart or kidney dysfunction worsens each other. This study aimed to explore the improvement effect of nicorandil on cardiorenal injury in patients with type I CRS. Patients with coronary heart disease complicated with type I CRS were enrolled. Based on the conventional treatment, the patients were prospectively randomized into a conventional treatment group and a nicorandil group, which was treated with 24 mg/d nicorandil intravenously for 1 week. Fasting peripheral venous blood serum and urine were collected before and at the end of treatment. An automatic biochemical analyzer and enzyme linked immunosorbent assay were used to detect B-type brain natriuretic peptide (BNP), serum creatinine (Scr) and cystatin C (Cys-C), renal injury index-kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), and interleukin-18 (IL-18) levels. The left ventricular ejection fraction was measured by echocardiography. All measurements were not significantly different between the nicorandil and conventional treatment groups before treatment (all P > 0.05), and BNP, Scr, Cys-C, NGAL, KIM-1, and IL-18 were decreased in the 2 groups at the end of treatment (all P < 0.05). Compared with the conventional treatment group, BNP, Scr, Cys-C, NGAL, KIM-1, and IL-18 were more significantly decreased in the nicorandil group (all P < 0.05) and left ventricular ejection fraction was more significantly increased (P < 0.05). Therefore, nicorandil could significantly improve the cardiac and renal function of patients with type I CRS. This may prove to be a new therapeutic tool for improving the prognosis and rehabilitation of type I CRS.

Nicorandil prevents the nephrotoxic effect of cyclosporine-A in albino rats through modulation of HIF-1α/VEGF/eNOS signaling

Despite that cyclosporine-A (CsA) is a widely used immunosuppressive drug, its nephrotoxic effect limits its long-term administration. Herein we tried to investigate its renal effect on endothelial dysfunction targeting the hypoxia-inducible factor (HIF-1α) / vascular endothelial growth factor (VEGF) / endothelial nitric oxide synthase (eNOS) pathway and the possible modulation by nicorandil. Eight groups of adult male Wistar rats were included: (1) control; (2) vehicle group (received oil); (3) glibenclamide 5 mg·kg-1·day-1 administered orally; (4) nicorandil 10 mg·kg-1·day-1 administered orally; (5) CsA 25 mg·kg-1·day-1 administered orally; (6) combined administration of CsA and nicorandil; (7) glibenclamide was added to CsA; and (8) both CsA and nicorandil were combined with glibenclamide. The treatment continued for six weeks. Combined nicorandil with CsA improved renal function deterioration initiated by CsA. CsA decreased the renal expression levels (P < 0.001) of HIF-1α, eNOS, and VEGF, inducing endothelial dysfunction and triggering inflammation, and upregulated the profibrotic marker transforming growth factor (TGF-β). Nicorandil fixed the disturbed HIF-1α/VEGF/eNOS signaling. Nicorandil corrected the renal functions, confirmed by the improved histological glomerular tuft retraction that was obvious in the CsA group, without significant influence by glibenclamide. Proper protection from CsA-induced nephrotoxicity was achieved by nicorandil. Nicorandil reversed the disturbed HIF-1α/VEGF/eNOS pathway created by CsA.

Hypothesis: The potential therapeutic role of nicorandil in COVID-19

At present, there is yet no specific antiviral treatment or immunization against the newly identified human severe acute respiratory syndrome virus (SARS-CoV2) that results in a rapidly progressive pandemic coronavirus disease 2019 (COVID-19). We believe in a crucial need for a clinical strategy to counteract this viral pandemic based on the known pathogenesis throughout the disease course. Evidence suggests that exaggerated patient's inflammatory response and oxidative stress are likely to aggravate the disease pathology. The resulting endothelial dysfunction further induces fibrosis and coagulopathy. These disturbances can generate severe acute respiratory distress syndrome (ARDS) that can progress into respiratory and circulatory failure. Nicorandil is an anti-anginal vasodilator drug acts by increasing nitric oxide bioavailability and opening of the KATP channel. Recently, nicorandil has been recognized to possess multiple protective effects against tissue injury. Here, we address a possible modulatory role of nicorandil against COVID-19 pathogenesis. We hypothesise nicorandil would be an effective form of adjuvant therapy against COVID-19.

Association between exercise intensity and renal blood flow evaluated using ultrasound echo

BACKGROUND

High-intensity exercise reduces renal blood flow (RBF) and may transiently exacerbate renal dysfunction. RBF has previously been measured invasively by administration of an indicator material; however, non-invasive measurement is now possible with technological innovations. This study examined variations in RBF at different exercise intensities using ultrasound echo.

METHODS

Eight healthy men with normal renal function (eGFR_cys 114 ± 19 mL/min/1.73 m²) participated in this study. Using a bicycle ergometer, participants underwent an incremental exercise test using a ramp protocol (20 W/min) until exhaustion in Study 1 and the lactate acid breaking point (LaBP) was calculated. Participants underwent a multi-stage test at exercise intensities of 60, 80, 100, 120, and 140% LaBP in Study 2. RBF was measured by ultrasound echo at rest and 5 min after exercise in Study 1 and at rest and immediately after each exercise in Study 2. To determine the mechanisms behind RBF decline, a catheter was placed into the antecubital vein to study vasoconstriction dynamics.

RESULTS

RBF after maximum exercise decreased by 51% in Study 1. In Study 2, RBF showed no significant decrease until 80% LaBP, and showed a significant decrease (31%) at 100% LaBP compared with at rest (p < 0.01). The sympathetic nervous system may be involved in this reduction in RBF.

CONCLUSIONS

RBF showed no significant decrease until 80% LaBP, and decreased with an increase in blood lactate. Reduction in RBF with exercise above the intensity at LaBP was due to decreased cross-sectional area rather than time-averaged flow velocity.