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Biomedical subjects

M Marcondes

Publications and source records attributed to M Marcondes.

At least 55 records · Page 3Linked to original sources
PubMed1986

Distal nephron sodium handling by normal, nephrotic, pyelonephritic and partially nephrectomized rats.

The renal tubular handling of sodium was evaluated in 10 normal (N), 9 edematous nephrotoxic serum nephrotic (Ne), 9 pyelonephritic (Py) and 12 partially nephrectomized (Nx) Wistar rats during maximal free-water clearance induced by intravenous infusion of hypotonic sodium chloride solutions. Fractional deliveries of sodium to distal nephron [(CH2O + CNa)/GFR%] were similar (P greater than 0.05) in N (23.2 +/- 0.69%), Ne (24.3 +/- 1.30%) and Nx (26.9 +/- 2.6%) rats. However, the fractional distal sodium reabsorption [CH2O/(CH2O + CNa)%] was significantly higher (P less than 0.05) in Ne (76.8 +/- 1.80%) and lower (P less than 0.05) in Nx (33.3 +/- 3.1%) rats when compared to normal rats (50.3 +/- 1.80%). Py rats exhibited a higher fractional delivery of sodium to distal nephron (33.5 +/- 3.4%) and a lower fractional distal sodium reabsorption (35.9 +/- 5.9%) when compared to normal rats (P less than 0.05). These data suggest that the distal nephron, by altering sodium reabsorption, contributes to the maintenance of sodium balance in Nx rats, whereas in Ne rats the distal nephron generates a positive sodium balance and edema. At very low glomerular filtration rates (GFR), as is the case for Py rats, sodium balance is maintained both by the proximal and distal portions of the nephron.

Animals↗
PubMed1985

Atrial natriuretic factor and generalized edema in rats.

The natriuretic action of the atrial natriuretic factor (ANF) was studied in massively proteinuric, anti-natriuretic and edematous nephrotic rats with moderate impairment of renal function. Animals were distributed among four groups: NA----NR, NV----NR, NeA----NR and NA----NeR, where normal atrial (NA) or normal ventricular (NV) or "nephrotic" atrial (NeA) extracts were injected (----) into normal rats (NR) or nephrotic rats (NeR). Control (C) clearance measurements were made before iv injection of the extracts and at four 15-min intervals thereafter (E). Mean arterial pressure and glomerular filtration rate did not change consistently in all four groups from the C to the E period. However, during the first 15-min period after extract injection, statistically significant fractional natriuretic peaks of 332, 361 and 662% of preinjection control values were demonstrable for the NA----NR, NeA----NR and NA----NeR groups, respectively, but not for NV----NR. Following the natriuretic peak, natriuresis returned to control values for NA----NR, but remained above control levels for the NeA----NR and NA----NeR groups. We conclude that, since both the atrial extract from nephrotic rats injected into normal rats and the atrial extract from normal rats injected into nephrotic rats elicited marked natriuresis, the anti-natriuretic edematous condition observed in nephrotic animals cannot be attributed either to the absence of ANF in their atria or to the unresponsiveness of their kidneys to ANF.

Animals↗
PubMed1984

Effects of vasoactive drugs on the natriuresis of nephrotic rats.

Seven nephrotic rats with edema, massive proteinuria and reduced glomerular filtration rate and filtration fraction were compared with ten normal rats. The experiment consisted of three consecutive periods: C, control; Ach, in which acetylcholine (40-60 ng/min) was continuously infused directly into the left renal artery; and Ach-AN-NA, in which angiotensin II (AN, 0.025 ng/min) + noradrenaline (NA, 0.25 micrograms/min) was systemically infused to elevate blood pressure, without interrupting acetylcholine infusion. Mean arterial pressure (MAP) and renal function parameters were measured. In both groups, MAP remained unchanged from C to Ach (P greater than 0.05) and was increased (P less than 0.05) from Ach to Ach-AN-NA (136 +/- 3.3 to 148 +/- 2.9 mmHg in normal animals, and 132 +/- 5.8 to 148 +/- 4.9 mmHg in nephrotic animals). In the normal group, intrarenal acetylcholine infusion increased (P less than 0.05) natriuresis from 3.75 to 7.93 microEq min-1 kd-1 kg BW-1 and a further, but transitory, increment up to 10.20 microEq min-1 kd-1 kg BW-1 was observed (P less than 0.05) when MAP was elevated. These natriuretic changes occurred without alterations of glomerular filtration rate (P greater than 0.05). Therefore, as previously reported in the literature, normal rats were responsive to intrarenal infusion of acetylcholine (vasodilator) followed by increased blood pressure, a condition known as pressure natriuresis. However, no natriuretic response was observed in the nephrotic group either to intrarenal acetylcholine infusion or to blood pressure elevation. We assume that nephrotic rats are insensitive to pressure natriuresis.

Acetylcholine↗
PubMed1981

Percutaneous transluminal angioplasty of renal artery stenosis.

Percutaneous transluminal angioplasty was performed in 7 patients with hypertension and renal artery stenosis, caused by atherosclerosis in 3 patients and fibromuscular disease in 4. The balloon dilatation was successful in all patients. In 6 patients the blood pressure was normalized within 5 days after the procedure, and remained so in 5 on follow up 3 to 10 months later.

Adolescent↗
PubMed1981

Effect of volume expansion on tubular reabsorption of protein by normal and nephrotic rats.

1. Normal (N) and nephrotic (NS) rats were infused with hyperoncotic human serum albumin or isotonic saline to alter plasma albumin concentration. The renal handling of albumin was evaluated by measuring the albumin/inulin clearance ratio (CA/CIN). The dextran/inulin clearance ratio, CD/CIN, was determined using dextran of 16,000 (14C) and 70,000 (3H) molecular weight. Five groups of rats were studied: NaA, NaS, NSaA, NdS and NSdS. The subscripts A and S indicate albumin and saline infusion; the superscripts a and d denote the measurement of CA/CIN and CD/CIN. 2. When vascular volume was expanded by infusion of albumin or saline, diuresis was increased in all groups (P less than 0.05). Inulin clearance was increased (P less than 0.05) in all groups except NaS, for which it was unchanged. The CA/CIN ratio was increased (P less than 0.05) for the three groups measured, NaA, NaS, and NSaA and the increase was independent of changes in plasma albumin concentration. In contrast, C16D/CIN decreased for NdS and NSdS and C70D/CIN decreased for NSdS but was unchanged for the NdS group. 3. The increase of CA/CIN could not be correlated with high albumin load, since it was also observed when plasma albumin was lowered by saline infusion. CD/CIN did not increase with saline infusion. Therefore an increase in glomerular permeability due to the volume expansion could not explain the increase in CA/CIN during albumin infusion. 4. We conclude that the depression of albumin reabsorption was a consequence of volume expansion. A model is presented which accounts for the effect of increased tubular flow on albumin reabsorption.

Animals↗
PubMed1979

Long-lasting inhibition of angiotensin response in rats by depot administration of octanoyl-[Leu8]-angiotensin II.

Depot administration of a lipophilic angiotensin II (AII) antagonist was tested for obtaining prolonged inhibition of the pressor response to AII in rats. Intramuscular injections of 1.5 or 5.0 mg of octanoyl-[Leu8]AII (oct-LAII), in oil solution produced the same degree of AII inhibition either 6 h or 24 h after the injection. The inhibition was comparable to that expected from the continuous intravenous infusion of oct-LAII at the rate of 1.2 microgram kg-1 min-1. The prolonged effect of intramuscular injections of oct-LAII in oil solution may be useful for chronic studies of physiopathological states involving the renin-angiotensin-aldosterone system.

Angiotensin II↗
PubMed1979

Lack of evidence for hepatic control of renal sodium excretion in rats.

Three experimental protocols were used: a) normal and partially hepatectomized rats were expanded with isotonic saline; b) normal rats were expanded with isotonic saline; b) normal rats were infused with hypertonic saline (5%), either by the femoral or portal vein and c) hypertonic saline was sequentially and alternatively infused into normal rats via portal and femoral veins. All the experiments were made under anesthesia. Inulin clearance and absolute and fractional urinary sodium and potassium excretion were measured. Multiple analysis of variance was made to compare normal and partially hepatectomized rats, as well as portal and femoral infusions made either in the same or in different animals. In none of these experiments it was possible to demonstrate an effect of the liver in enhancing the natriuresis induced by saline infusions.

Animals↗
PubMedDate not supplied

Antidiuretic action of chlorpropamide in diabetes insipidus patients and in normal subjects.

The antidiuretic action of chlorpropamide was studied in 10 diabetes insipidus patients sensitive to vasopressin and 15 normal subjects. After an oral load of water followed by sustained hydration through water ingestion in a volume equivalent to the urinary flow, chlorpropamide (4 mg/kg body weight) was intravenously administered as a single dose, either alone (34 experiments) or simultaneously with pitressin infusion (6 experiments). During the experiments, creatinine clearance as well as osmolal and plasma and urine electrolyte concentrations were measured. Several urine collection periods were made before and after the administration of chlorpropamide. In thes experimental conditions, chlorpropamide promoted a marked antidiuresis (p less than 0.01) in patients with diabetes insipidus and presented no antidiuretic effect (p greater than 0.01) in normal subjects, even with a double dose. However, if previously to the experiment, the normal individuals were dehydrated (mean weight loss of 4.8 per cent) or the diabetes insipidus patients were hydrated (mean weight gain of 6.4 per cent) a reverse behavior was observed: that is, the normal subjects did present (p less than 0.01) and the diabetes insipidus patients did not present (p greater than 0.01) antidiuresis to chlorpropamide. The results suggest that the state of hydration modulates the action of chlorpropamide in a way apparently independent of the antiduretic hormone.

Chlorides↗
PubMedDate not supplied

Progressive hypervolemia despite hypoproteinemia and massive edema formation in rats with nephrotoxic serum nephritis.

Blood volume and whole kidney and single nephron function were evaluated 2 and 10 days after nephrotoxic serum nephritis (NSN) induction in Wistar rats. Progressive proteinuria, hypervolemia and edema were observed in NSN rats. Sodium retention was associated with a progressive depression of single nephron glomerular filtration rate and elevated fractional tubular reabsorption rates. Since hypervolemia rather than hypovolemia was observed in this study, edema formation must have been a consequence of intrarenal rather than extrarenal phenomena.

Animals↗
PubMedDate not supplied

Nephrotic syndrome associated with hepatointestinal schistosomiasis.

Schistosomal nephropathy has long been related to the hepatosplenic form of schistosomiasis. In the last few years, 24 patients with hepatointestinal schistosomiasis and the nephrotic syndrome were studied. Aiming at evaluating a possible etiologic participation of schistosomiasis in the development of the nephropathy, this group was comparatively studied with a group of 37 patients with idiopathic nephrotic syndrome. Both groups had a different distribution of the histologic lesions. In the group with schistosomiasis there was a statistically significant prevalence of proliferative mesangial glomerulonephritis (33.3%), whereas in the control group there was prevalence of membranous glomerulonephritis (32.4%). On immunofluorescence, IgM was positive in 94.4% of the patients with schistosomiasis versus 55.0% in the control group (P < 0.01). In the group with schistosomiasis, 8 patients evidenced mesangial proliferative glomerulonephritis and 5, membranoproliferative glomerulonephritis. In both histological types immunofluorescence showed IgM and C3 granular deposits in the glomeruli. The data in this study suggests that mesangial proliferative and membranoproliferative glomerulonephritis, with glomerular granular IgM and C3 deposits, represent the renal lesions of the schistosomiasis associated nephropathy.

Adolescent↗
PubMedDate not supplied

Seasonal variation of blood pressure in maintenance hemodialysis.

CONTEXT: Seasonal variation in arterial blood pressure has been reported in studies with hypertensive and normotensive subjects. However, the influence of seasonal change on blood pressure of hemodialysis patients has not been reported. OBJECTIVE: To investigate the seasonal variation of blood pressure in Brazil, a tropical country, in patients on hemodialysis. DESIGN: Prospective, cohort study. SETTING: Dialysis unit of a tertiary medical center (a teaching hospital of the University of São Paulo School of Medicine, São Paulo). PATIENTS: Sixteen patients with chronic renal failure undergoing hemodialysis. OUTCOMES: Blood pressure, body weight, and ambient temperature were evaluated during 6 hemodialysis sessions carried out on 13 days during the four seasons. RESULTS: The diastolic blood pressure was lower in summer than in fall and winter (95 +/- 8 vs 107 +/- 10 and 101 +/- 10 mmHg, respectively; p < 0.05). The same was observed with mean blood pressure (116 +/- 8 vs 130 +/- 11 and 124 +/- 9 mmHg, respectively; p < 0.01). On the other hand, the ambient temperature was higher in summer than in fall and winter (23.0 +/- 1.6 vs 19.5 +/- 3.0 and 15.8 +/- 1.9 degrees C, respectively; p < 0.01). CONCLUSIONS: We concluded that for patients with chronic renal failure the blood pressure has a seasonal variation with higher pressures in fall and winter than in summer. Thus, further studies are needed to elucidate the impact of this observation on the adjustment of antihypertensive treatment and on morbidity and mortality in maintenance dialysis patients.

Adult↗
PubMedDate not supplied

[Treatment of essential hypertension and hypercholesterolemia with or without hypertriglyceridemia, with low dose of bezafibrate (200 mg/day)].

Twenty patients with essential hypertension, 5 with dyslipidemia type IIa and 15 with that of type IIb, were treated with bezafibrate, 200 mg/day. As control group, 20 normo or dislipemic patients with essential hypertension receiving no hypolipidemic drugs, and chosen at random, showed no significant changes of the mean values of serum total cholesterol and triglycerides at three evaluations made in a period of about six months. Six patients were males (60 +/- 4 years) and 14 females (57 +/- 2 years). The levels of cholesterolemia and triglyceridemia were evaluated before the administration of the drug and on the 28th and 56th day of its use. The mean initial value of total cholesterol (n = 20) was 334 +/- 10 mg/dl, lowering significantly (P less than 0.01) to 274 +/- 7 mg/dl and 279 +/- 11 mg/dl. Initial triglyceridemia level (n = 15) was 544 +/- 85 mg/dl, decreasing significantly (P less than 0.01) to 234 +/- 36 and 245 +/- 36. Percentual mean decrease of cholesterolemia was respectively 16 +/- 4% and 14 +/- 5% and that of triglyceridemia was 46 +/- 8% for both evaluations. Side effects of the drug were not seen with the indicated dose. The therapy was useful to lower the dislipemic values of the essential hypertensive patients, in spite of no consistent changes in their diet and physical activity and of its use for a short period.

Aged↗