Yayoi Ishikawa

Fasudil, a Rho-kinase inhibitor, attenuates glomerulosclerosis in Dahl salt-sensitive rats.

Objective The present study was designed to clarify whether the Rho–Rho-kinase pathway is involved in the process of hypertensive glomerulosclerosis and to assess the therapeutic effect of fasudil, a specific Rho-kinase inhibitor. Method and results Dahl salt-sensitive rats (DS) and Dahl salt-resistant rats (DR) were fed a high-salt diet at 6 weeks of age. Fasudil (30 mg/kg per day) was administered for 7 weeks to DS starting at the age of 11 weeks. After 7 weeks, untreated DS were characterized by decreased kidney function, increased proteinuria, abnormal morphological findings, increased adrenomedullin and atrial natriuretic peptide (ANP) levels, and increased renal messenger RNA expression of RhoB, Rho-kinaseα, Rho-kinaseβ, collagen I and collagen III, and transforming growth factor-beta (TGF-β) in the renal cortex compared with DR. Chronic fasudil treatment significantly improved renal function (serum creatinine, –26%; blood urea nitrogen, –41%; creatinine clearance, +42%), proteinuria (–24%) and histological findings (glomerular injury score, –49%; afferent arteriolar injury score, –17%) without changing blood pressure compared with untreated DS. Interestingly, long-term fasudil treatment decreased the plasma adrenomedullin (–25%) and ANP (–49%), but did not change the plasma renin or aldosterone. Furthermore, fasudil significantly decreased the messenger RNA expression of TGF-β (–20%), collagen I (–23%), and collagen III (–24%) in the renal cortex. However, there were still significant differences in the aforementioned parameters between DR and fasudil-treated DS. Conclusion These results suggest that the Rho–Rho-kinase pathway may be partly responsible for the pathogenesis of hypertensive glomerulosclerosis independently of blood pressure in DS, and that chronic inhibition of the Rho–Rho-kinase pathway may be a new strategy for treating hypertensive nephrosclerosis.

Long-Term Administration of Rho-Kinase Inhibitor Ameliorates Renal Damage in Malignant Hypertensive Rats

We have shown recently that fasudil, a Rho-kinase inhibitor, has renoprotective effects in salt-sensitive hypertensive rats. We hypothesized that activation of Rho-kinase is involved in the pathogenesis of glomerulosclerosis in malignant hypertensive rats. To test this hypothesis, we studied the following 4 groups: control Wistar–Kyoto rats, untreated deoxycorticosterone-acetate salt spontaneously hypertensive rats (DOCA-SHR), low-dose fasudil-treated DOCA-SHR, and high-dose fasudil-treated DOCA-SHR. After 3 weeks of treatment, the effects of fasudil were examined. DOCA-SHR was characterized by increased blood pressure (BP); increased kidney weight; decreased renal function; increased proteinuria; abnormal histological findings; increased monocyte/macrophage infiltration; increased urinary 8-isoprostran levels; increased gene expression of collagen I, collagen III, transforming growth factor-β, and reduced nicotinamide-adenine dinucleotide phosphate oxidase subunits (p40phox, p47phox, and p67phox); and decreased gene expression of endothelial NO synthase (eNOS) in the renal cortex as compared with Wistar–Kyoto rats. Long-term high-dose fasudil treatment significantly improved renal function and histological findings without changing BP, as compared with untreated DOCA-SHR. Interestingly, long-term fasudil treatment significantly decreased monocyte/macrophage infiltration and urinary 8-isoprostran excretion, in association with decreased mRNA levels of transforming growth factor-β, collagen I, collagen III, and NADPH oxidase subunits (p40phox, p47phox, and p67phox), and increased mRNA levels of eNOS in the renal cortex. Long-term low-dose fasudil treatment tended to improve these variables slightly but did not affect most of them significantly. Our results suggest that long-term fasudil treatment provides renoprotective effects independent of BP-lowering activity. These renoprotective effects are associated with inhibition of extracellular matrix gene expression, monocyte/macrophage infiltration, oxidative stress, and upregulation of eNOS gene expression.

Alteration of renal adrenomedullin and its receptor system in the severely hypertensive rat: effect of diuretic

OBJECTIVE We investigated the pathophysiological role of the renal adrenomedullin (AM) system, including the ligand, receptor, and amidating activity, in severe hypertensive rats. METHOD We studied three groups: control Wistar Kyoto rats (WKY), spontaneously hypertensive stroke-prone rats (SHR-SP), and diuretic-treated SHR-SP. We measured AM-mature, active form, and AM-total (active form+inactive form) in plasma and renal tissues, and mRNA levels of AM and AM receptor system components such as calcitonin receptor-like receptor (CRLR), receptor activity-modifying protein (RAMP) 2, and RAMP3 in renal tissues. RESULTS SHR-SP had higher blood pressure, plasma neurohumoral factors, and lower renal function than WKY. SHR-SP had higher AM-mature and AM-total levels in plasma and renal tissues than WKY. Although the plasma AM-mature/AM-total ratio was similar in the two groups, AM-mature/AM-total ratio in renal tissues was higher in SHR-SP than in WKY. In addition, mRNA levels of AM in the renal cortex and medulla and the mRNA levels of CRLR, RAMP2, and RAMP3 in the renal cortex were higher in SHR-SP than in WKY. Chronic diuretic treatment decreased blood pressure and improved kidney function and neurohumoral factors, with reductions in plasma and renal AM system. CONCLUSION Upregulation of circulating and renal AM system may modulate pathophysiology in SHR-SP.

Two Molecular Forms of Adrenomedullin in Congenital Heart Disease

To investigate the pathophysiological role of two forms of adrenomedullin (AM), a mature AM (AM-m) and a glycine-extended AM (AM-Gly), in congenital heart disease, we measured plasma levels of AM in patients with cyanotic heart disease, high pulmonary blood flow without pulmonary hypertension (PH), high pulmonary blood flow with PH, Fontan procedure, intracardiac repair without complication, and intracardiac repair with PH and control subjects. Plasma AM-m and AM-Gly were increased only for cyanotic heart disease (2. 5 ± 1.3 pmol/L, p < 0.001; 13.1 ± 6.2 pmol/L, p < 0.05) and intracardiac repair with PH (2.3 ± 1.5 pmol/L, p < 0.01; 13.0 ± 7.0 pmol/L, p < 0.05) compared with control (1.0 ± 1.4 and 8.6 ± 1.3 pmol/L, respectively). They were similarly correlated with mean systemic arterial pressure (r = −0.40 and −0.37 respectively; p < 0.001), mixed venous oxygen saturation (r = −0.60 and −0.50; p < 0.0001), systemic arterial oxygen saturation (SAsat) (r = −0.56 and −0.46; p < 0.0001), and pulmonary arterial resistance (Rp) (r = 0.41 and 0.38; p < 0.005). Multiple regression analysis revealed that SAsat and Rp were independently correlated with AM. Interestingly, the venous AM-m level was significantly higher than the arterial AM-m, suggesting that the mature form is extracted in pulmonary circulation, whereas there were no venoarterial differences in AM-Gly. These results suggest that plasma AM-m and AM-Gly are similarly regulated and the main clearance site of AM-m is the lung in patients with congenital heart disease.