Chronic consumption of three forms of palm oil diets alters glomerular filtration rate and renal plasma flow.

The effects of chronic consumption of three types of palm oil diets on glomerular filtration rate (GFR), renal plasma flow (RPF) and blood pressure were studied. Wistar rats were randomly assigned into four groups of ten rats each, respectively: control, fresh (FPO), photoxidized (PPO), thermoxidized (TPO) palm oil diet-fed rats. The control group was fed rat chow only, while experimental groups had different palm oil diets at 15% wt/wt for twelve weeks and tap water ad libitum. After the feeding period, GFR, RPF, systolic and diastolic blood pressures were measured. GFR and RPF of the TPO (0.07 ± 0.01 ml/min and 1.50 ± 0.24 ml/min) and PPO (0.14 ± 0.01 and 2.54 ± 0.11) groups were significantly (p < 0.001) reduced compared with control (0.77 ± 0.04 and 5.3 ± 0.30) and FPO (0.81 ± 0.02 and 4.8 ± 0.13) groups. The GFR and RPF of the TPO group was significantly (p < 0.05) higher than that of the PPO group. Systolic and diastolic blood pressures of the TPO group (140 ± 3 mmHg and 106 ± 4 mmHg) were significantly (p < 0.01) increased when compared with the control (112 ± 6.4 and 78 ± 5), FPO (118 ± 5 and 81 ± 6) and PPO (122 ± 5 and 89 ± 5) groups. These results suggest that chronic consumption of TPO and PPO caused a decrease in GFR and RPF, but increased blood pressure in rats, while FPO did not adversely affect blood pressure, GFR and RPF.

[Alteration of renal hemodynamic in adriamycin-induced nephrosis rats administrated with Wulingsan].

OBJECTIVE: To investigate the effect of traditional classical compound Wulingsan on renal hemodynamic in rats with adriamycin (ADR)-induced nephrosis. METHOD: After establishing a model of rats with adriamycin-induced nephrosis, we administrated wulin-san to the ADR rats via oral gavage for four weeks and measured mean arterial blood preasure (MABP) with manometer. Renal clearance of paraaminohippuric acid (PAH) and inulin were detected, then renal plasma flow (RPF) and glomerular filtration rate (GFR) were calculated. Renal vascular resistance (RVR) was calculated as the division of MABP by RPF. Renal endothelin (ET) and angiotensin II (Ang II) were detected with radioimmunity assay kits, and nitrous oxide (NO) was detected with biochemical kits. RESULT: There was no significant change of GFR in ARD rats, but RPF and NO were decreased, which accompanied by enhanced RVR, ET and Ang II. RPF was increased in the administrated rats, in company with RVR, ET and Ang II decreased, whereas NO was not influenced after the administration. CONCLUSION: Wulingsan can improve the renal hemodynamic in ADR rats, at least in part by modulating the levels of vasoactive factor.

Effects of creatine supplementation on body composition and renal function in rats.

BACKGROUND: The aim of the present study was to evaluate the long-term effects of oral creatine supplementation on renal function and body composition (fat and lean mass) in an experimental model. METHODS: Male Wistar rats were supplemented with creatine (2 g.kg(-1) of food) for 10 wk in combination with treadmill exercise, 12 m.min(-1), 1 h.d(-1) (CREAT + EX, N = 12) or not (CREAT, N = 10), and compared with exercised animals without creatine supplementation (EX, N = 7) and CONTROL animals, N = 7. Body composition and bone mineral density (BMD) were determined by dual x-ray absorptiometry and glomerular filtration rate (GFR) and renal plasma flow (RPF) were measured by inulin and paraaminohippurate clearance, respectively. RESULTS: At the end of the study (post), CREAT+EX presented higher lean mass and lower fat mass than CREAT, EX or CONTROL (349.7 +/- 19.7 vs 313.3 +/- 20.3, 311.9 +/- 30.8, 312.4 +/- 21.0 g and 5.7 +/- 2.3 vs 10.0 +/- 3.3, 9.8 +/- 1.5, 10.0 +/- 3.5%, P < 0.05, respectively). Post lean/fat mass ratio was higher than baseline only in CREAT + EX (18.9 +/- 7.2 vs 8.6 +/- 1.8, P < 0.05). Post BMD was significantly higher than baseline in all groups. GFR and RPF were lower in CREAT versus CONTROL (0.5 +/- 0.1 vs 1.0 +/- 0.1 and 1.5 +/- 0.2 vs 2.4 +/- 0.5 mL.min(-1), P < 0.05, respectively). CONCLUSION: Creatine supplement in combination with exercise increased the proportion of lean mass more than EX or CREAT alone. The use of creatine alone induced an important and significant reduction of both RPF and GFR.

Renal and haemodynamic effects of amlodipine and nifedipine in hypertensive renal transplant recipients.

BACKGROUND: Immunosuppressive treatment with cyclosporin A (CsA) improves the survival of renal allografts, but is associated with renal vasoconstriction and hypertension. Previous reports suggest that the calcium-channel blockers nifedipine and amlodipine may improve graft function in CsA-treated patients. We have compared the effects of amlodipine (5-10 mg once daily) and nifedipine retard (10-40 mg twice daily) on renal function and blood pressure in renal transplant recipients treated with CsA. METHODS: This was a multicentre, two-way, crossover study in 27 evaluable hypertensive patients with renal insufficiency following renal transplantation, who were maintained on a stable dose of CsA. Patients received either amlodipine (5-10 mg once daily) or nifedipine retard (10-40 mg twice daily) for 8 weeks, and were then crossed over to the other treatment for a further 8 weeks. RESULTS: Trends were seen during amlodipine treatment towards larger improvements, in serum creatinine (by 8% of baseline on amlodipine vs 4% on nifedipine), lithium clearance (13% vs 2%), and glomerular filtration rate 11% vs 7%). Effective renal plasma flow was increased by 11% of baseline on nifedipine vs 9% on amlodipine. There were no significant differences between treatments. Amlodipine and nifedipine lowered systolic blood pressure to a similar extent (21 mmHg vs 15 mmHg respectively, P=0.25), but amlodipine was more effective than nifedipine in lowering diastolic blood pressure (13 mmHg vs 8 mmHg, P=0.006). Both treatments were well tolerated. CONCLUSION: Once-daily amlodipine is at least as effective as twice-daily nifedipine retard in controlling blood pressure and does not adversely affect graft function in hypertensive renal allograft recipients.

How should we treat hypertensive women with cardiac and renal impairment?

Arterial hypertension is the most common chronic medical condition requiring office visits to physicians and is a major contributing factor to the development of myocardial infarction and stroke. Its importance as a cardiovascular risk factor is at least as significant in women as in men; however, the ever-growing literature on hypertension shows surprisingly little data concerning sex differences. Large clinical trials of antihypertensive treatment have not clearly demonstrated gender differences in blood pressure response and outcome, but the majority of patients in these trials were men. Even so, some evidence indicates that white women treated for hypertension obtain less benefit than men. The pathophysiology of hypertension in men and women is similar in many aspects, but important gender differences are now emerging. Studies designed to clarify these differences are required, as a better knowledge of the underlying mechanisms will allow for a more precise stratification of risk and a more accurate approach to both nonpharmacologic and pharmacologic treatment.

Kidney function in cyclosporine-treated pediatric heart transplant recipients.

BACKGROUND: End-stage kidney disease may develop in 1% to 3% of cyclosporine-treated heart transplant recipients, and most patients show a decreased glomerular filtration rate. There are little data on kidney function in pediatric recipients, although good function is needed for their optimal development. METHODS: Kidney function was prospectively investigated in 10 children receiving triple immunosuppression (cyclosporine, azathioprine, methylprednisolone) during the first 18 months after heart transplantation. The early cyclosporine trough level target was 300 to 500 micrograms/L and 100 to 200 micrograms/L after the first year. 51Chromium-ethylenediamine tetraacetic acid, para-amino hippuric acid, lithium, and sodium clearances, measurements of serum and urinary electrolytes, and urinary concentration tests were performed. Renal biopsy specimens were obtained from four patients after 18 months. RESULTS: Heart function was good in all patients. Six patients (60%) remained rejection-free at 18 months. The mean glomerular filtration rate was 92.4 ml/min/1.73 m2 before transplantation, increased to 115 by 6 months (p < 0.05), and thereafter remained stable. The mean renal plasma flow was 487 ml/min/1.73 m2 after 18 months. Hypertension was seen in all patients at discharge but in only one at 18 months. Mild hyperuricemia was the most common sign of tubular dysfunction occurring in five patients at discharge but in only two patients at 18 months. The result of kidney histopathologic study was normal in three of four patients, and cyclosporine nephrotoxicity was not diagnosed. CONCLUSIONS: Triple immunosuppression with cyclosporine adequately protects the graft against acute rejection. It is compatible with normal glomerular function and leads to only minor tubular disturbances.

Comparative effects of dopexamine and dopamine on glycerol-induced acute renal failure in rats.

Acute renal failure (ARF) was induced in rats by intramuscular injection of 50% glycerol, 10 mL/kg body weight. Rats were given isotonic saline (1.5 mL/h) dopexamine hydrochloride (dopexamine, 100 microg/h) or dopamine (100 microg/h), commencing either immediately after glycerol administration and maintained during all the observation time (90 min, acute studies) or 20 min before administration of glycerol and during 60 min (chronic studies). Renal function was assessed during 90 min after induction of ARF in anesthetized rats and during 3 days following ARF induction in conscious animals. In anesthetized rats treated with dopexamine or dopamine, the reduction in insulin and para-aminohippuric acid clearance was markedly lower than that observed in untreated animals. In conscious animals, urinary flow and creatinine clearance were higher in rats treated with dopamine or dopexamine than in the non-treated group. Rats treated with dopexamine had higher renal Na+ and K+ excretion than dopamine-treated rats. Survival was higher in the dopexamine group than in either of the other two groups. These results demonstrate that pretreatment with dopexamine or dopamine significantly improves the course of ARF, with better survival after treatment with dopexamine.

Renal functional reserve in calcium channel blocker-treated hypertensive recipients of kidney transplant.

Renal functional reserve during infusion of an amino acid solution was examined in 12 cyclosporin-treated kidney recipients at 1 (T1) and 8 months (T2) after transplantation. Patients were retrospectively divided into six normotensive (NT) and six hypertensive recipients (HT) maintained on monotherapy with a calcium channel blocker. Baseline glomerular filtration rates (GFR) were similar in NT and HT at T1 and T2. Renal functional reserve was identical in NT and HT at T1 (15 +/- 7 vs 18 +/- 13 ml/min/1.73 m2) but significantly greater in HT at T2 (11 +/- 5 vs 23 +/- 10 ml/min/1.73 m2; P < 0.05). At T2, baseline proximal tubule outflow (lithium clearance) was greater in HT (26 +/- 8 vs 16 +/- 3 ml/min/1.73 m2; P < 0.05), whereas fractional proximal reabsorption was less (54 +/- 11% vs 67 +/- 5%; P < 0.05). These results indicate that: (i) hypertensive recipients on calcium channel blocker therapy do not exhibit permanent glomerular hyperfiltration until 8 months after transplantation, and have a reduced proximal reabsorption; (ii) measurement of amino acid-stimulated GFR and renal functional reserve is a more sensitive method than that of baseline GFR for evaluating renal function and the effects of therapy in kidney recipients.

Long-term treatment with nifedipine reduces urinary albumin excretion and glomerular filtration rate in normotensive type 1 diabetic patients with microalbuminuria.

The aim of the present study was to investigate the renal effects of long-term treatment with the calcium channel blocker nifedipine in normotensive type 1 diabetic patients with microalbuminuria. In a randomized, double-blind trial, 15 type 1 diabetic patients were treated with either nifedipine (n = 8; dosage 30 mg/day) or placebo (n = 7) for 12 months. At baseline and after 6 and 12 months of therapy, the albumin excretion rate (UAER, radioimmunoassay), glomerular filtration rate (GFR, chromium 51 ethylenediamine tetra-acetic acid clearance) and renal plasma flow (RPF, iodine 125 hippuran clearance) were determined. Nifedipine treatment caused a significant reduction of UAER after 6 and 12 months (median, Q1/Q3 in mg/24 h): baseline 84 (65/163); 6 months 35 (23/90), P < 0.02; 12 months 39 (15/79), P < 0.05). GFR was significantly decreased by nifedipine treatment (baseline 157 +/- 15, 6 months 122 +/- 8, 12 months 111 +/- 47 ml/min; P < 0.05, mean +/- SEM), whereas RPF remained constant. Nifedipine treatment did not influence systolic (baseline 121 +/- 7, 12 months 124 +/- 2 mmHg, mean +/- SEM) or diastolic (baseline 72 +/- 2, 12 months 74 +/- 3 mmHg) arterial blood pressure. With placebo treatment no significant alterations of UAER, GFR, RPF and arterial blood pressure were observed. Metabolic control was constant throughout the whole study period. Thus, 1 year's treatment with nifedipine reduces the UAER and GFR in normotensive type 1 diabetic patients without influencing the systemic arterial blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Hypercalciuric response to dietary supplementation with DL-methionine and ammonium sulfate.

Renal Ca and inorganic P (Pi) excretion were evaluated in Single Comb White Leghorn pullets reared on diets containing 1 or 3.5% Ca alone or supplemented with .6% DL-methionine or .53% ammonium sulfate. Plasma and urine samples were collected during a CONTROL period, and while 200 mM Ca was infused intravenously (Ca-LOADING). Excess Ca, whether supplied chronically in the feed or infused acutely into birds fed 1% Ca diets, significantly reduced glomerular filtration rates, effective renal plasma flow rates, and Pi excretion rates and significantly increased Ca excretion rates and urine pH. Birds fed diets supplemented with DL-methionine and ammonium sulfate maintained significantly lower plasma Ca concentrations during the CONTROL and Ca-LOADING periods than birds fed the respective 1 or 3.5% Ca basal diets. When compared with birds fed the respective 1 or 3.5% Ca basal diets, birds fed the 1% Ca diet supplemented with ammonium sulfate or the 3.5% Ca diet supplemented with DL-methionine had significantly higher absolute urinary Ca excretion rates during Ca-LOADING. Fractional Ca excretion during Ca-LOADING was significantly higher in birds fed 3.5% Ca supplemented with DL-methionine or ammonium sulfate than in birds fed the 3.5% Ca basal diet. These results indicate that DL-methionine and ammonium sulfate accelerated urinary Ca excretion and reduced Ca retention in the extracellular fluid. The hypercalciuric efficacies of DL-methionine and ammonium sulfate were revealed only when the filtered load of Ca was increased through intravenous Ca infusions.

Renal responses to acute angiotensin II inhibition and administered angiotensin II in the aging, conscious, chronically catheterized rat.

Studies of conscious, chronically catheterized, young (3 to 5 months of age) and old (19 to 22 months of age) male Sprague Dawley rats in the baseline state showed that glomerular filtration rate (factored for body weight) was lower and urine flow higher in old compared with young rats. Acute blockade of endogenous angiotensin II (AII) with either converting enzyme inhibitor (CEI) or Losartan (Dupont Merck, Wilmington, DE) caused small variable decreases in blood pressure in both age groups and produced a significant renal vasodilation with increases in renal plasma flow in the older rats. In separate studies using low-dose AII infusion (5 ng/kg body weight/min), an increase in filtration fraction was the only effect seen in both young and old rats with an intact renin/AII system; no effect was seen with CEI. During high-dose AII (20 ng/kg body weight/min), significant and similar increases were seen in blood pressure and renal vascular resistance in old and young rats, and the patterns of blood pressure and renal hemodynamic responses were similar with and without acute CEI. A natriuretic and diuretic response to high-dose AII was seen in young rats with intact endogenous renin/AII, whereas old rats were completely refractory to this action of AII. Against a background of acute CEI, no natriuretic/diuretic response to high-dose AII was seen in either age group. Thus, in the baseline state, renal hemodynamics in the old kidney are controlled by endogenous AII since CEI and Losartan produce renal vasodilation in old but not young rats.(ABSTRACT TRUNCATED AT 250 WORDS)