Assessment of Nephroprotective Potential of Histochrome during Induced Arterial Hypertension.

Magnetic resonance tomography was employed to verify endothelial dysfunction of renal arteries in Wistar and OXYS rats under conditions of induced arterial hypertension. Angiography revealed changes in the size and form of renal arteries of hypertensive animals. In hypertensive rats, histochrome exerted a benevolent therapeutic effect in renal arteries: it decreased BP, diminished thrombus formation in fi ne capillaries and arterioles, demonstrated the anticoagulant properties, partially improved endothelial dysfunction of small renal arteries, and up-regulated the glomerular filtration.

Comparative study of transcatheter renal arterial embolization with and without closed renal circuit: pharmacokinetic and histologic assessment in pigs.

PURPOSE: To assess the degree of renal necrosis and the leakage of absolute ethanol by using two methods: transcatheter renal artery embolization (TAE) and TAE performed with a closed renal circuit (CRC) (TAE/CRC), both performed by using ethanol and iodized oil, in a pig model. MATERIALS AND METHODS: All animal experiments were conducted in accordance with our university guidelines for animal care and experimentation. Fourteen pigs were classified in two groups: standard TAE and TAE/CRC groups. In the TAE/CRC group, the renal artery and vein were occluded with balloon catheters; in the TAE group, only the renal artery was occluded. An emulsion of absolute ethanol (0.5 mL per kilogram of body weight) and iodized oil (emulsion ratio, 4:1) was injected in the renal artery in both groups. In the TAE/CRC group, we aspirated the blood containing the emulsion via the renal vein during arterial infusion. We measured the ethanol concentrations of the systemic circulation. Four days after embolization, the kidneys in both groups were removed and histopathologic examination was performed and results were compared. RESULTS: The mean systemic ethanol concentration was less than 0.1 mg/mL in the TAE/CRC group and 0.28 mg/mL +/- 0.15 (standard deviation) in the TAE group (P < .002). In both groups, about 90% of the kidney was shown histopathologically to have undergone coagulation necrosis (no significant difference). The frequency of venous thrombus formation was significantly lower (P = .009) in the TAE/CRC group. CONCLUSION: TAE/CRC dramatically reduces ethanol leakage to the systemic circulation without a decrease in embolization effect in the normal swine kidney, and it also reduces the likelihood of venous thrombus formation.

Assessment of the effect of radio contrast media on resistive index of renal artery by color doppler sonography.

Renal ischemia and direct toxic effect of contrast media are the main confounding causes of contrast-induced nephropathy (CIN). The effect of different contrast mediums on the resistance of renal artery is quite unclear. The aim of the present study was to assess the resistive index (RI) changes of renal segmental artery in color Doppler duplex sonography after injection of two different contrast mediums: iodixanol and iohexol. The RI of the renal segmental artery of 62 randomly chosen patients, with a normal baseline renal function, was calculated using color-coded Doppler sonography before and five minutes after bolus injection of two different contrast mediums. Thirty-one patients were administered 50 mL of iodixanol (Visipaque) and 31 patients were administered 50 mL of iohexol (Omnipaque) during intravenous urogram procedures. The RI results were analyzed and compared in two groups using two-tailed t-test. The mean RI of renal segmental artery increased significantly after administration of contrast media (mean +/- SD 0.61 +/- 0.046 vs 0.58 +/- 0.042; p< 0.001). The mean change of RI was 0.0387 +/- .00552 (mean +/- SE) in the setting of iohexol injection and 0.0216 +/- .00423 (mean +/- SE) five minutes after administration of iodixanol (p= 0.017). Both non-ionic iso-osmolar dimeric iodixanol and low-osmolar iohexol increase the renal artery resistance, but the changes are more dramatic with iohexol, suggesting better tolerance with iodixanol.

Assessment of renal hemodynamic effects of nesiritide in patients with heart failure using intravascular Doppler and quantitative angiography.

OBJECTIVES: We evaluated the magnitude and site of action of the nesiritide mediated renal vasodilatory effect in patients with heart failure (HF). BACKGROUND: Nesiritide, a recombinant human B-type natriuretic peptide is approved for the treatment of acute decompensated HF and has been shown to exert favorable hemodynamic, neurohormonal, and symptomatic effects. The renal effect of nesiritide in HF patients has not been well defined. METHODS: In 15 patients with acute decompensated HF, intravascular Doppler and quantitative angiography of the renal artery were used to assess the effect of nesiritide on renal artery diameter and velocity time integral as well as renal blood flow and vascular resistance. Nesiritide was administered intravenously at a standard dose of 2 microg/kg bolus followed by a continuous infusion at a rate of 0.01 microg/kg/min. Assessment of nesiritide effect was made at 15 min. RESULTS: Nesiritide infusion was associated with a significant central hemodynamic effect including a fall in mean pulmonary artery pressure (36 +/- 12 mm Hg to 31 +/- 13 mm Hg, p < 0.001), mean pulmonary capillary wedge pressure (21 +/- 2 mm Hg to 15 +/- 10 mm Hg, p < 0.001), and systemic vascular resistance (1,995 +/- 532 dynes s cm(-5) to 1,563 +/- 504 dynes s cm(-5), r < 0.001), and an increase in cardiac output from 3.9 +/- 1.2 l/min to 4.6 +/- 1.6 l/min (p = 0.001). Nesiritide was also associated with a significant vasodilatory effect on the large conductance renal arteries resulting in an increase in renal artery diameter from 6.2 +/- 0.7 mm to 6.7 +/- 0.8 mm (p < 0.001). At the same time, there was a concomitant fall in mean renal artery pressure (99 +/- 17 mm Hg to 89 +/- 13 mm Hg, p = 0.002) and renal blood flow velocity time integral (27 +/- 15 cm/beat to 23 +/- 15 cm/beat, p = 0.008) and, therefore, no significant change in renal blood flow or renal vascular resistance. CONCLUSIONS: The nesiritide effect on the renal circulation in patients with HF is complex, with a marked vasodilatory action on the large, conductance renal arteries but a concomitant fall in velocity time integral and no effect on renal vascular resistance or renal blood flow. Lack of increase in renal blood flow may be due to a fall in renal blood pressure or an intrarenal vasoconstrictive effect.

[Effect of propranolol on renal hemodynamics in patients with cirrhosis: assessment with Doppler US]. / Siroz hastalarinda propranololün renal hemodinamik etkileri: Doppler US ile degerlendirme.

PURPOSE: To determine the renal resistive index profile in cirrhotic patients before and after propranolol treatment and assess the effects of propranolol on renal hemodynamics. MATERIALS AND METHODS: Thirty-six patients with cirrhosis and ascites (decompensated group), 39 patients with cirrhosis but no ascites (compensated group) and 25 patients with normal renal and hepatic functions (control group) were studied. All had normal blood urea nitrogen and serum creatinine levels. The renal resistive index was calculated in all patients before and after oral propranolol treatment. RESULTS: Resistive index was significantly higher in the decompensated group (p<0.05) than in other groups. After propranolol treatment, resistive indices decreased in the compensated patients (p<0.05) but increased in the decompensated group (p<0.05). There was a slight but statistically insignificant increase in the control group. CONCLUSION: In patients with cirrhosis renal failure is a significant risk factor for liver transplantation. In these patients, Doppler sonography provides early detection of renal dysfunction even before renal function tests are abnormal. Doppler sonography is a useful noninvasive method to evaluate the effects of drugs on renal hemodynamics.

Assessment of nephrotoxicity in the chick embryo: effects of cisplatin and 1,2-dibromoethane.

Morphological symptoms of mesonephric kidney damage were analysed in chick embryos treated with nephrotoxic agents--CDDP or DBE. The drugs were administered intraamniotically on ED 3 at doses 0.03 and 0.3 microg CDDP or 100 and 300 microg DBE per embryo. Body weight and absolute and relative measures of the mesonephroi (length, weight and form) were evaluated on ED 10. The higher doses of both agents affected the mass of this organ significantly. Simultaneously, a dose-dependent increase of renal malformations was detected in treated embryos, while the incidence of gross and cardiovascular defects was low (DBE) or absent (CDDP). Together with less pronounced effects on the total body growth, the results gave evidence for a higher sensitivity of the mesonephros to toxic insult when compared to the whole organism. A direct cytotoxic effect multiplied by concomitant injury of blood supply seemed to be the main cause of CDDP nephrotoxicity. In the case of DBE, damage to the mesonephros was probably associated with a primary impairment of the vascular network. The chick embryo in ovo provides a promising system for the assessment of nephrotoxic effects induced by prospective therapeutic agents and environmental contaminants during the prenatal period.

Assessment of radiocontrast media induced renal vasoconstriction by color coded duplex sonography.

INTRODUCTION: Changes in renal hemodynamics are suspected to be one of the major pathogenetic correlates in radiocontrast media-induced nephrotoxicity. We investigated whether color-coded duplex sonography is an appropriate method to document changes in intrarenal vascular resistance, after intravenous injection of the low-osmolar contrast material lopamidol. METHODS: Intrarenal arterial doppler wave forms were analyzed every minute after intravenous injection of 100 mL lopamidol in 10 patients during a voiding cystourogram-procedure. The Resistive Index (RI) of each flow curve, reflecting intrarenal flow resistance, was calculated and compared to the mean of four RI measurements taken before contrast media application. RESULTS: One minute after injection of Iopamidol the RI remained unchanged compared to the baseline standard of 0.70. In measurements obtained 2, 3, 4, and 5 minutes after lopamidol injection a statistically significant rise was seen: (minute 2: 0.74, p < 0.001/minute 3: 0.75, p = 0.001/minute 4: 0.72, p =0.018/minute 5: 0.74, p = 0.031). During the further course, the resistive indices decreased progressively and showed no significant difference in comparison with the baseline standard value. CONCLUSION: Color coded duplex sonography is a simple method to detect changes in renal flow resistance after application of radiocontrast media. Based on our results, we believe that the analysis of intrarenal arterial doppler flow profiles constitutes an ideal method to investigate pathophysiologic mechanisms of radiocontrast media-induced nephrotoxicity, as well as pharmacological concepts in nephroprotectivity.

Low-dose dopamine after kidney transplantation: assessment by Doppler ultrasound.

Low-dose dopamine (LDD) is commonly used after kidney transplantation as a renoprotective agent, although the benefits of dopamine (DA) in this setting are controversial. LDD increases renal blood flow, decreases resistive index (RI) and causes diuresis in normal kidneys. We hypothesised that the vasculature of a denervated renal transplant may not respond to DA in the same way as healthy native kidneys. In a prospective, controlled study, renal blood flow velocity and vascular resistance were measured by Doppler ultrasound in recent kidney transplants (n = 20) over a range of DA doses (0-5 microg/kg/min). Main renal artery velocity was lower in kidneys with acute renal dysfunction than in those with normal function (0.60 +/- 0.31 vs. 0.81 +/- 0.24, respectively, p < 0.05). There was no demonstrable haemodynamic effect of LDD on either RI or main renal artery velocity as measured by Doppler ultrasound. Interestingly, the only significant correlation with mean RI was trough cyclosporin A level (r = 0.57, p < 0.001). Technical or timing factors cannot be used to explain the absence of DA effect, with equivalent doses capable of producing vasodilatation and reduced RI in studies of normal kidneys. In summary, these findings contrast the DA response of healthy native kidneys and may explain studies showing no clinical benefit of LDD in the early post-transplant period. These data suggest an insensitivity of recently implanted kidneys to the vasodilatory effects of LDD, that other factors such as cyclosporin A vasoconstriction may also be important, and question the rationale for routine LDD after kidney transplantation.

Renal artery vasomotion: in vivo assessment in the pig with intravascular Doppler.

Intravascular Doppler is widely used for experimental studies in the coronary circulation. We designed this study to assess baseline bloodflow and arteriolar resistance in the porcine renal circulation and to study the vasomotor responses of vasoactive drugs. In anesthesized piglets (n = 15), renal arterial diameter was measured with quantitative angiography and blood flow velocity with a Doppler wire (Cardiometrics). Bloodflow and resistances were calculated at baseline and after injection of vasoactive drugs (isosorbide dinitrate, papaverine). This allowed us to determine the renal bloodflow reserve (the capacity of the kidney to augment basal bloodflow). Injection of isosorbide dinitrate was associated with an increase in average peak velocity of 64% (P < 0.01) and a small (from 4.5 to 4.74, P < 0.01) but significant increase in renal artery diameter, resulting in an increase in bloodflow of 82% (P < 0.01) and a decrease in arteriolar resistance of 46% (P < 0.01). Bloodflow returned to baseline (4.76 +/- 1.48 mL/s) approximately 5 min after isosorbide injection. Average Peak Velocity increased almost twofold after papaverine injection (60 +/- 10 to 108 +/- 24 cm/sec, P < 0.01). There was a significant (P < 0.01) increase in arterial bloodflow of 96% in the right and 79% in the left renal artery after injection of papaverine with a corresponding significant (P < 0.01) decrease in arteriolar resistance of 49% in the right and 44% in the left renal artery. Using a combination of quantitative angiography and intravascular Doppler allows easy measurement of baseline renal blood flow and of the effects of vasodilator drugs on bloodflow and resistance. The results show that a vasodilatator reserve exists in the renal circulation but is less marked than that reported in the coronary circulation.