Ischemic acute renal failure (ARF) is a highly complex disorder involving renal vasoconstriction, filtration failure, tubular obstruction, tubular backleak and generation of reactive oxygen species. Due to this complexity, the aim of our study was to explore effects of Angiotensin II type 1 receptor (AT1R) blockade on kidney structure and function, as well as oxidative stress in spontaneously hypertensive rats (SHR) after renal ischemia reperfusion injury. Experiments were performed on anaesthetized adult male SHR in the model of ARF with 40 minutes clamping the left renal artery. The right kidney was removed and 40 minutes renal ischemia was performed. Experimental groups received AT1R antagonist (Losartan) or vehicle (saline) in the femoral vein 5 minutes before, during and 175 minutes after the period of ischemia. Biochemical parameters were measured and kidney specimens were collected 24h after reperfusion. ARF significantly decreased creatinine and urea clearance, increased LDL and lipid peroxidation in plasma. Treatment with losartan induced a significant increase of creatinine and urea clearance, as well as HDL. Lipid peroxidation in plasma was decreased and catalase enzyme activity in erythrocytes was increased after losartan treatment. Losartan reduced cortico-medullary necrosis and tubular dilatation in the kidney. High expression of pro-apoptotic Bax protein in the injured kidney was downregulated after losartan treatment. Our results reveal that angiotensin II (via AT1R) mediates the most postischemic injuries in hypertensive kidney through oxidative stress enhancement. Therefore, blockade of AT1R may have beneficial effects in hypertensive patients who have developed ARF.

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The ideal agent for prevention and treatment of uterine abnormal contractility has not been found. The polyphenol resveratrol possesses a wide spectrum of pharmacologic properties, but its influence on the contractility of human myometrium is not defined. The present study evaluated the effect of resveratrol on the oxytocin-induced contractions of human term pregnant myometrium in vitro and the contribution of different K(+) channels to resveratrol action. Resveratrol induced a concentration-dependent relaxation of myometrium contractions (pD2 value and maximal responses were 4.52 and 82.25%, respectively). Glibenclamide, a selective blocker of ATP-sensitive (KATP), iberiotoxin, a selective blockers of big-calcium sensitive (BK(Ca)) and 4-aminopiridine, a non-selective blocker of voltage-sensitive (Kv) channels induced a significant shift to the right of the concentration-response curves of resveratrol. Inhibition achieved by 0.1 mM resveratrol was insensitive to all K(+) channel blockers. A K(+) channel opener, pinacidil, inhibited oxytocin-induced contractions of pregnant myometrium with comparable potency and efficacy to resveratrol (pD2 values and maximal relaxation were 4.52 and 83.67%, respectively). Based on K(+) channel opener/blocker affinities, it appears that the inhibitory response of resveratrol involves different myometrial K(+) channels. When applied in high concentrations, resveratrol has an additional K(+)-channel-independent mechanism(s) of action. Furthermore, immunohistochemistry staining and western blot analyses detected the presence and distribution of KATP, BK(Ca) and Kv channel proteins in pregnant myometrium.

Because adrenergic contractions can contribute to the development of life-threatening spasm of coronary artery bypass graft, this study was performed to investigate the effect of adenosine 3-phosphate (ATP)-sensitive K channel (KATP) opener P1075 on contractions of isolated human saphenous vein (HSV) and human internal mammary artery (HIMA). Phasic contractions were evoked by electric field stimulation (20 Hz) and noradrenaline. The sustained contractions were evoked by phenylephrine. The presence of pore-forming Kir6.1 and Kir6.2 subunits of the KATP channels in the HIMA and only Kir6.2 in the HSV was confirmed immunomorphologically. P1075 inhibited in the HSV only, the electrical field stimulation contractions more strongly than noradrenaline contractions. In addition, the phenylephrine contractions of HSV were more sensitive to P1075 in comparison to those of HIMA. Glibenclamide, a KATP channel blocker antagonized the vasodilatation produced by P1075 in both grafts differently, because its effect was more prominent on the P1075-induced inhibition of contractions of HSV than of HIMA. We conclude that P1075 has a vasorelaxant effect and inhibited adrenergic contractions of the tested grafts. This effect is graft and vasoconstrictor selective and seems to be mediated by Kir6.1- and/or Kir6.2-containing KATP channels. Thus, P1075 can be considered as a potential drug in the prevention of graft spasm.

Rare neural cell adhesion molecule (NCAM) positive cells have been previously described within the normal human adult kidney interstitium, speculating that they could increase in the interstitium with incipient interstitial renal fibrosis (IRF). In the present study, among 93 biopsy samples of various kidney diseases, NCAM+ interstitial cells were detected in 62.4% cases. An increased number of NCAM+ cells was significantly observed only in incipient IRF compared to normal renal tissues and advanced IRF stages (p<0.001), independently of underlying diseases (p = 0.657). All three major NCAM isoforms’ RT-PCR bands were visible either in normal or in kidneys with incipient IRF, albeit their mRNA expression levels measured by qRT-PCR were different. Applying qRT-PCR on pure NCAM+ cells population, obtained by laser capture microdissection, significant mRNA over-expression of NCAM140kD isoform was found in NCAM+ cells within incipient IRF (p = 0.004), while NCAM120kD and NCAM180kD isoforms were not changed significantly (p = 0.750; p = 0.704; respectively). Simultaneously, qRT-PCR also showed significant αSMA (p = 0.014) and SLUG (p = 0.004) mRNAs up-regulation within the NCAM+ cells of incipient IRF, as well as highly decreased matrix metalloproteinases (MMP) -2 and -9 mRNAs (p = 0.028; p = 0.036; respectively). However, using double immunofluorescence MMP-9 could still be detectable on the protein level in rare NCAM+ cells within the incipient IRF. Further characterization of NCAM+ cells by double immunofluorescent labeling revealed their association with molecules involved in fibrosis. Fibroblast growth factor receptor 1 (FGFR1) and α5β1 integrin were extensively expressed on NCAM+ cells within the incipient IRF areas, whereas human epididymis protein-4 (HE4) was found to be present in few NCAM+ cells of both normal and interstitium with incipient fibrosis. Heterogeneity of NCAM+ interstitial cells in normal and incipient IRF, concerning molecules related to fibrosis and variable expression of NCAM isoforms, could suggest diverse role of NCAM+ cells in homeostasis and in regulation of renal fibrosis in diseased kidneys.