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Renal Vascular Resistance (renal + vascular_resistance)
Selected AbstractsExtracorporeal Support: Improves Donor Renal Graft Function After Cardiac DeathAMERICAN JOURNAL OF TRANSPLANTATION, Issue 6 2010A. Rojas-Pena Donors after cardiac death (DCD) could increase the organ pool. Data supports good long-term renal graft survival. However, DCDs are <10% of deceased donors in the United States, due to delayed graft function, and primary nonfunction. These complications are minimized by extracorporeal support after cardiac death (ECS-DCD). This study assesses immediate and acute renal function from different donor types. DCDs kidneys were recovered by conventional rapid recovery or by ECS, and transplanted into nephrectomized healthy swine. Warm ischemia of 10 and 30 min were evaluated. Swine living donors were controls (LVD). ECS-DCDs were treated with 90 min of perfusion until organ recovery. After procurement, kidneys were cold storage 4,6 h. Renal vascular resistance (RVR), urine output (UO), urine protein concentration (UrPr) and creatinine clearance (CrCl), were collected during 4 h posttransplantation. All grafts functioned with adequate renal blood flow for 4 h. RVR at 4 h posttransplant returned to baseline only in the LVD group (0.36 mmHg/mL/min ± 0.03). RVR was higher in all DCDs (0.66 mmHg/mL/min ± 0.13), without differences between them. UO was >50 mL/h in all DCDs, except in DCD-30 (6.8 mL/h ± 1.7). DCD-30 had lower CrCl (0.9 mL/min ± 0.2) and higher UrPr >200 mg/dL, compared to other DCDs >10 mL/min and <160 mg/dL, respectively. Normothermic ECS can resuscitate kidneys to transplantable status after 30 min of cardiac arrest/WI. [source] Nitric oxide, superoxide and renal blood flow autoregulation in SHR after perinatal L -arginine and antioxidantsACTA PHYSIOLOGICA, Issue 4 2007M. P. Koeners Abstract Aim:, Nitric oxide (NO) and superoxide are considered to be regulatory in renal blood flow (RBF) autoregulation, and hence may contribute to development of hypertension. To extend our previous observations that dynamic NO release is impaired in the spontaneously hypertensive rat (SHR) we investigated, firstly, if superoxide dependency of RBF autoregulation is increased in SHR and, secondly, if the beneficial effect of perinatal supplementation in SHR is partly as a result of early correction of RBF autoregulation. We hypothesized that perinatal supplementation by restoring dynamic NO release and/or decreasing superoxide dependency and would improve life-long blood pressure regulation. Methods:, Autoregulation was studied using stepwise reductions in renal perfusion pressure in anaesthetized male SHR, SHR perinatally supplemented with arginine and antioxidants (SHRsuppl) and Wistar-Kyoto (WKY), prior to and during i.v. N, -nitro- l -arginine (NO synthase inhibitor) or tempol (superoxide dismutase mimetic). Results:, Spontaneously hypertensive rat displayed a wider operating range of RBF autoregulation as compared with WKY (59 ± 4 vs. 33 ± 2 mmHg, respectively; P < 0.01). Perinatal supplementation in SHR decreased mean arterial pressure, renal vascular resistance and the operating range of RBF autoregulation (43 ± 3 mmHg; P < 0.01). In addition autoregulation efficiency decreased. RBF autoregulation characteristics shifted towards those of normotensive WKY. However, dynamic NO release was still impaired and no clear differences in superoxide dependency in RBF autoregulation between groups was observed. Conclusion:, Perinatal supplements shifted RBF autoregulation characteristics of SHR towards WKY, although capacity of the SHRsuppl kidney to modulate NO production to shear stress still seems impaired. The less strictly controlled RBF as observed in perinatally supplemented SHR could result in an improved long-term blood pressure control. This might partly underlie the beneficial effects of perinatal supplementation. [source] Dopamine increases renal oxygenation: a clinical study in post-cardiac surgery patientsACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 2 2010BENGT REDFORS Background: Imbalance of the renal medullary oxygen supply/demand relationship can cause ischaemic acute renal failure (ARF). The use of dopamine for prevention/treatment of ischaemic ARF has been questioned. It has been suggested that dopamine may increase renal oxygen consumption (RVO2) due to increased solute delivery to tubular cells, which may jeopardise renal oxygenation. Information on the effects of dopamine on renal perfusion, filtration and oxygenation in man is, however, lacking. We evaluated the effects of dopamine on renal blood flow (RBF), glomerular filtration rate (GFR), RVO2 and renal O2 demand/supply relationship, i.e. renal oxygen extraction (RO2Ex). Methods: Twelve uncomplicated, mechanically ventilated and sedated post-cardiac surgery patients with pre-operatively normal renal function were studied. Dopamine was sequentially infused at 2 and 4 ug/kg/min. Systemic haemodynamics were evaluated by a pulmonary artery catheter. Absolute RBF was measured using two independent techniques: by the renal vein thermodilution technique and by infusion clearance of paraaminohippuric acid (PAH), with a correction for renal extraction of PAH. The filtration fraction (FF) was measured by the renal extraction of 51Cr-EDTA. Results: Neither GFR, tubular sodium reabsorption nor RVO2 was affected by dopamine, which increased RBF (45,55%) with both methods, decreased renal vascular resistance (30,35%), FF (21,26%) and RO2Ex (28,34%). The RBF/CI ratio increased with dopamine. Dopamine decreased renal PAH extraction, suggestive of a flow distribution to the medulla. Conclusions: In post-cardiac surgery patients, dopamine increases the renal oxygenation by a pronounced renal pre-and post-glomerular vasodilation with no increases in GFR, tubular sodium reabsorption or renal oxygen consumption. [source] The renal effects of alginates isolated from brown seaweed Sargassum vulgareJOURNAL OF APPLIED TOXICOLOGY, Issue 3 2008Alessandra de Paula Alves Sousa Abstract Alginates isolated from Sargassum vulgare, present a strong antitumor activity, associated with kidney reversible damage, as analysed by histopathology of treated animals. In the present study, the renal alteration mechanisms of S. vulgare alginates were investigated using the isolated perfused rat kidney and the isolated perfused rat mesenteric blood vessel methods. The results showed that the effects of Sargassum vulgare low viscosity (SVLV) alginate were more potent than those of Sargassum vulgare high viscosity (SVHV) alginate in the isolated rat kidney. The SVLV alginate caused considerable changes in renal physiology, as shown by an increase in parameters such as perfusion pressure, renal vascular resistance, glomerular filtration rate, urinary flow and sodium, potassium and chloride excretion and by reduction of chloride tubular transport. The effects of SVHV were weaker than those of SVLV. The effects of SVLV on kidney could be related to direct vascular action as demonstrated with SVLV alginate on mesenteric blood vessels. In conclusion, the Sargassum vulgare alginate altered the renal function parameters evaluated. S. vulgare low viscosity alginate renal effects were more potent than S. vulgare high viscosity alginate. It is suggested that physicochemical differences between SVHV and SVLV could explain the differences found in the results. Copyright © 2007 John Wiley & Sons, Ltd. [source] Low-dose vasopressin increases glomerular filtration rate, but impairs renal oxygenation in post-cardiac surgery patientsACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 8 2009G. BRAGADOTTIR Background: The beneficial effects of vasopressin on diuresis and creatinine clearance have been demonstrated when used as an additional/alternative therapy in catecholamine-dependent vasodilatory shock. A detailed analysis of the effects of vasopressin on renal perfusion, glomerular filtration, excretory function and oxygenation in man is, however, lacking. The objective of this pharmacodynamic study was to evaluate the effects of low to moderate doses of vasopressin on renal blood flow (RBF), glomerular filtration rate (GFR), renal oxygen consumption (RVO2) and renal oxygen extraction (RO2Ex) in post-cardiac surgery patients. Methods: Twelve patients were studied during sedation and mechanical ventilation after cardiac surgery. Vasopressin was sequentially infused at 1.2, 2.4 and 4.8 U/h. At each infusion rate, systemic haemodynamics were evaluated by a pulmonary artery catheter, and RBF and GFR were measured by the renal vein thermodilution technique and by renal extraction of 51chromium,ethylenediaminetetraacetic acid, respectively. RVO2 and RO2Ex were calculated by arterial and renal vein blood samples. Results: The mean arterial pressure was not affected by vasopressin while cardiac output and heart rate decreased. RBF decreased and GFR, filtration fraction, sodium reabsorption, RVO2, RO2Ex and renal vascular resistance increased dose-dependently with vasopressin. Vasopressin exerted direct antidiuretic and antinatriuretic effects. Conclusions: Short-term infusion of low to moderate, non-hypertensive doses of vasopressin induced a post-glomerular renal vasoconstriction with a decrease in RBF and an increase in GFR in post-cardiac surgery patients. This was accompanied by an increase in RVO2, as a consequence of the increases in the filtered tubular load of sodium. Finally, vasopressin impaired the renal oxygen demand/supply relationship. [source] Acute systemic, splanchnic and renal haemodynamic changes induced by molecular adsorbent recirculating system (MARS) treatment in patients with end-stage cirrhosisALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 5 2007G. DONATI Summary Aim To evaluate the acute effect of treatment with the molecular adsorbent recirculating system (MARS) on splanchnic, renal and systemic haemodynamics in patients with end-stage cirrhosis. Methods Twelve patients with end-stage cirrhosis, undergoing MARS treatment, were enrolled. The following haemodynamic parameters were measured by means of Doppler ultrasonography and thoracic electrical bioimpedance, before and after each session: portal velocity, renal and splenic resistance indices, cardiac output, cardiac stroke volume, heart rate, mean arterial pressure, systemic vascular resistance. Results Median portal velocity increased significantly after treatment (23.7 vs. 20.3 cm/s, P < 0.05) while renal resistance index (0.72 vs. 0.75, P < 0.05) and splenic resistance index (0.60 vs. 0.65, P < 0.05) decreased significantly. Mean arterial pressure (83 vs. 81 mmHg, P < 0.05) and vascular resistance (899 vs. 749 dyne. s/cm5, P < 0.05) increased significantly, while cardiac output and stroke volume showed no significant changes. Conclusions Data emerging from this investigation suggest that MARS treatment improves significantly various haemodynamic alterations in cirrhotic patients in the short term. The observed decrease in renal vascular resistance and improvement in splenic resistance index, a parameter related to portal resistance, which leads us to hypothesize that these haemodynamic effects are probably mediated by clearance of vasoactive substances during MARS treatment. [source] Renal impairment in deoxycorticosterone acetate-salt hypertensive ratsNEPHROLOGY, Issue 4 2000Catherine Dallemagne Summary: This study has compared renal function in deoxycorticosterone (DOCA)-salt hypertensive Wistar rats (uninephrectomy followed by administration of DOCA 25 mg subcutaneously every fourth day and 1% NaCl in the drinking water) with various control rats using the isolated perfused kidney preparation. The systolic blood pressure of DOCA-salt hypertensive rats was 180 ± 10 mmHg (uninephrectomy controls: 136 ± 9 mmHg) while normalization of calcium intake (DOCA-Ca rats, 1% CaCl2 in water) attenuated this increase (systolic blood pressure, 146 ± 5 mmHg). Renal mass corrected for body weight increased by 25% after uninephrectomy, 55% in uninephrectomized rats given NaCl, 152% in DOCA-salt rats and 147% in DOCA-Ca rats. At a renal perfusion pressure of 135 mmHg, isolated perfused kidneys from DOCA-salt rats showed decreases of 48% in glomerular filtration rate and 69% in sodium excretion with an increase of 44% in renal vascular resistance compared with uninephrectomized rats. There were no significant differences in renal function between DOCA-salt and DOCA-Ca rats. Histological assessment of renal pathology showed proximal tubular hypertrophy and hyperplasia, marked focal distal tubular atrophy, interstitial fibrosis and glomerular hypercellularity in DOCA rats compared with UNX rats. Lesions were less obvious in UNX-salt or DOCA-Ca rats. The lack of direct correlation between alterations in function and pathology may be explained by the compensatory effect of remaining healthy or hypertrophied nephrons. Thus, the DOCA-salt model of hypertension in rats is associated with marked structural kidney damage and severely decreased kidney function. Marked attenuation of systemic hypertension by normalizing calcium intake in DOCA-salt rats did not prevent impairment of kidney function. [source] Perfusate Lactate Dehydrogenase Level and Intrarenal Resistance Could Not Be Adequate Markers of Perfusion Quality During Isolated Kidney PerfusionARTIFICIAL ORGANS, Issue 11 2000Berta Herrera Abstract: The main goal of this work was to study the influence of perfusion pressure and flow waveform during kidney perfusion, and the relationship between renal vascular resistance (RVR) and lactate dehydrogenase (LDH) concentration in the perfusate. Simultaneous constant pressure kidney perfusions were performed with either pulsatile or continuous flow at either 30 or 80 mm Hg of constant perfusion pressure. Mean flow, pressure, and RVR were displayed online during perfusion. Perfusate samples for LDH, creatine phosphatase kinase (CPK), and alkaline phosphatase (AP) determinations were taken. At the end of the perfusion, 2 ml of Evans blue was injected into the circuit to obtain images of perfusate distribution, and the kidneys were weighed. Also, hematoxylin/eosine studies were performed, showing more Bowman's space and tubular dilation in kidneys perfused with high pressure. We did not find differences in RVR between kidneys perfused at 30 and 80 mm Hg; nevertheless, perfusate distribution was better in the 80 mm Hg perfusions. We did not find any correlation between enzyme release and RVR in kidneys perfused with different mean pressures. These findings suggest that vascular resistance and LDH concentration cannot be independently considered as adequate markers of perfusate distribution. [source] Influence of high dietary sodium intake on the functional subtypes of ,1 -adrenoceptors in the renal cortical vasculature of Wistar,Kyoto ratsAUTONOMIC & AUTACOID PHARMACOLOGY, Issue 1-2 2009R. N. Kazi Summary 1,Increased renal vascular resistance is one renal functional abnormality that contributes to hypertension, and ,1 -adrenoceptors play a pivotal role in modulating this renal vascular resistance. This study investigates the functional contribution of ,1 -adrenoceptor subtypes in the renal cortical vasculature of Wistar,Kyoto rats on a normal sodium diet (WKYNNa) compared with those given saline to drink for 6 weeks (WKYHNa). 2,The renal cortical vascular responses to the adrenergic agonists noradrenaline (NA), methoxamine (ME) and phenylephrine (PE) were measured in WKYHNa and WKYNNa rats either in the absence (the control phase) or presence of chloroethylclonidine (CEC), an ,1B -adrenoceptor antagonist, 5-methylurapidil (5-MeU), an ,1A antagonist, or BMY7378, an ,1D antagonist. 3,Results showed a greater renal cortical vascular sensitivity to NA, PE and ME in the WKYHNa compared with WKYNNa rats (P < 0.05). Moreover, 5-MeU and BMY7378 attenuated adrenergically induced renal cortical vasoconstriction in WKYHNa and WKYNNa rats; this response was largely blunted in CEC-treated WKYHNa rats (all P < 0.05) but not in CEC-treated WKYNNa rats. 4,The data suggest that irrespective of dietary sodium content, in Wistar,Kyoto rats ,1A - and ,1D -subtypes are the major ,1 -adrenoceptors in renal cortical vasculature; however, there appears to be a functional involvement of ,1B -adrenoceptors in the WKYHNa rats. [source] | ||||||||||