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Kidney function during decreased perfusion pressure due to aortic clamping and hemorrhagic hypotension: a single nephron study in dog kidney.

Whole kidney and single nephron function was compared in dogs during a stepwise lowering of renal perfusion pressure (PP) induced by aortic clamping (C) or hemorrhagic hypotension (HH). In C, renal vascular resistance (RVR) decreased with decreasing PP, the decrease being due to a drop in afferent resistance (RA) only. HH was associated with a rise in RVR due in the first phase mainly to an increase in RE, later to both RA and RE. There was a decrease in total kidney blood flow (RBF), glomerular filtration rate (GFR), glomerular and peritubular capillary pressure, and proximal tubular pressure. In C, RBF and GFR showed no significant difference at PPs 17 and 13 kPa. However, single nephron pressures were slightly but significantly lowered. In both groups, glomerular capillary hydraulic pressure (GCP) was significantly higher when calculated as SFP + piA (stop flow pressure + systemic arterial plasma oncotic pressure) than when measured directly by puncturing glomerular capillaries after ablation of a small layer of superficial cortex. This difference disappeared at PP 8 kPa. Ultrafiltration coefficient (Kf) seemed to increase with decreasing PP.

Animals↗

Pathophysiology of water and sodium retention: edematous states with normal kidney function.

Body fluid volume regulation by the kidney relies upon the complex interaction of numerous factors. However, in edematous disorders, extrarenal factors can override the 'innate wisdom' of the kidney. For example, in patients with cardiac failure or liver disease and in pregnant women, the normal kidney continues to retain sodium and water despite expanded blood, plasma and extracellular fluid volumes. Such fluid retention can ultimately lead to pulmonary congestion, ascites or peripheral edema. Understanding the kidney's modulation of total body sodium and water in these patients has been perplexing. Cardiac output cannot provide the sole afferent signal for the kidney to regulate sodium and water balance, as the normal kidney can retain excessive amounts of sodium and water when cardiac output is low (e.g. in low output cardiac failure) or high (e.g. cirrhosis or pregnancy). Therefore the integrity of the arterial circulation, which can be impaired either by a low cardiac output or arterial vasodilation, is an important factor in body fluid composition and volume regulation in health and disease.

Atrial Natriuretic Factor↗

The influence of an angiotensin II antagonist, saralasin, given before donor nephrectomy, on kidney function after transplantation. A controlled prospective study.

Kidneys from cadaver donors who had been treated during the last 10 min before bilateral nephrectomy with an infusion of 10 micrograms/kg-1/min-1 (Sar1, Val5, Ala8)-angiotensin II had a remarkable, significantly lower percentage of acute renal failure (25%) after renal transplantation than untreated kidneys (58.3%). Anuria was seen in the treated group only in 4.2%, although it occurred in the untreated control group in 16.6%. The role of the activated renin-angiotensin system in postischemic acute renal failure is discussed.

Acute Kidney Injury↗

[Effect of septopal on kidney function during treatment of traumatic chronic inflammation of bones].

Treatments included 20 patients for whom in the marrow cavity 1 chain of Septopal was inserted, and 10 patients for whom 2-4 chains were inserted. Before the planned operation the mark of the level of urea and of creatinine in the blood serum was made for the patients, and the clearance of creatinine was calculated. It was stated that usage of Gentamycin-Septopal for people who do not let know about the suffering from a kidney disease in the past, and the laboratory tests before the operation do not show deviations from the standard is a safe treatment recommended in prophylaxis and in treatment of blood-derived and traumatic inflammations of bones. Because of nephrotoxicity of Gentamycin the function of kidneys should be monitored before and during treatment with that medicine. Gentamycin can be connected with other antibiotics in order to improve the efficiency of its work.

Chronic Disease↗

Support of kidney function by long-chain fatty acids derived from renal tissue.

To determine whether the oxidation of long-chain fatty acids (LCFA) derived from renal tissue lipids can support renal function, we perfused isolated rat kidneys with a substrate-free Krebs-Ringer bicarbonate solution containing 6 g/100 ml substrate-free (defatted) albumin. We measured GFR, TNa+, and Qo2 at 7-min intervals from 15 to 99 min after cannulation of the renal artery. Two groups (A and B) of 12 perfusions each were done. During substrate-free perfusion mean %TNa+ was low (A = 45 +/- 2%, B = 62 +/- 5%). When 10(-4) M 2-tetradecylglycidic acid (2-TDGA), a specific and irreversible inhibitor of long-chain acylcarnitine transferase-I, was added to the substrate-free perfusate, significant decreases in %TNa+ (A to approximately 25%; B to approximately 35%) and in Qo2 (delta = -25%) occurred. During perfusion with either 5 mM lactate or 5 mM alpha-ketoglutarate (alpha-KG) %TNa+ increased to approximately 80%. When 2-TDGA was added in the presence of lactate or of alpha-KG no decrease in %TNa+ or Qo2 occurred. Thus, 2-TDGA does not inhibit net renal Na+ transport or O2 uptake in the presence of high concentrations of lactate or alpha-KG, substrates not requiring long-chain acylcarnitine transferase for their utilization. We conclude that oxidation of LCFA released from renal tissue lipids can support a significant portion of Na+ reabsorption.

Animals↗

Intact kidney function during contralateral renal artery clamping in dogs.

Experiments were carried out on 32 Nembutal anaesthetized mongrel dogs from both sexes. After 45 min control period unilateral renal ischemia was achieved by clamping the left renal artery for 90 min. In part of the experiments (n = 8) after clamp removal 3 consecutive 45 min periods were performed. The function of the intact right kidney was investigated. Mean arterial pressure (MAP), heart rate (HR), glomerular filtration rate (GFR), urine flow rate (V), fractional excretions of sodium (FENa), potassium (FEK) and chloride (FECl) and plasma levels of atrial natriuretic peptide, dopamine and antidiuretic hormone were evaluated. During ischemia MAP was elevated from 122.5 +/- 3.1 to 140.2 +/- 2.7 mmHg (p < 0.001), HR decreased from 119 +/- 4 to 102.5 +/- 3.9 beats/min (p < 0.01) as compared to the control period. GFR did not change significantly, while all excretory parameters increased: V from 8.7 +/- 1.2 to 14.5 +/- 1.7 microliters/min/gr kidney tissue (p < 0.05); FENa from 2.3 +/- 0.2 to 3.6 +/- 0.3% (p < 0.01); FEK from 40.0 < 3.5 to 51.2 < 2.8% (p < 0.05); FECl from 1.8 < 0.3 to 2.6 < 0.3% (p < 0.05). MAP remained elevated in the first and the second postischemic periods and was paralleled by the sustained increase in FENa and FECl, while FEK remained higher to the end of the experiment. ANP was significantly elevated during ischemia: on 75 min--p < 0.01 and on 105 min.--p < 0.05. AVP and dopamine showed no statistically significant changes during the investigated periods.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

[New aspects of nuclear medicine diagnosis of kidney function: improved potential by pharmacologic intervention and quantitative analytic procedures].

In nuclear medicine new trends in the diagnosis of renal function are based on the introduction of new radiopharmaceuticals, improvements in the methodological part of the procedure and precise pharmacological intervention in response to given indications. Tc99m mercaptoacetyltriglycine (Tc99m MAG3) was tested as replacement for I123 orthoiodohippuric acid (I123 oIH) both in the form of a HPLC purified substance and as an impure kit preparation. HPLC purified Tc99m MAG3 clearance determinations in anuric patients showed a low extrarenal excretion amounting to only about 5% of the total clearance in normal patients. Kit preparations yielded about 90% of the labelled product; impurities were pertechnetate, reduced hydrolyzed Tc99m and chemically unidentified labelled products which showed a significantly lower renal, but increased hepatobiliary excretion in comparison with Tc99m MAG3. The renal clearance with kit preparations of Tc99m MAG3 was 55% of the clearance with oIH at a comparable urinary excretion. Significantly higher protein binding and therefore, a decrease in the distribution volume of Tc99m was found in comparison with I123 oIH. No difference was recorded between the two substances with respect to the renogram curves in normal subjects, apart from a modest delay in the elimination of Tc99m MAG3. For clinical purposes kit preparations of Tc99m MAG3 proved equal to I123 oIH. The influence of angiotensin converting enzyme (ACE) inhibitors (captopril) leads to characteristic changes in the renograms of patients with Goldblatt hypertension. Quantitative criteria for the evidence of haemodynamically significant renal artery stenosis were derived from investigations without and with captopril (25 mg) (I123 oIH and Tc99m DTPA) in 21 patients with essential hypertension. The criteria were defined as follows: a delay in peak activity (Tmax) in the I123 oIH captopril renogram exceeding 2 minutes as compared with the baseline value and/or a lower uptake of Tc99m DTPA in comparison with the uptake of I123 oIH (uptake quotient I123 oIH/Tc99m DTPA greater than 1.2). The diagnostic and prognostic potential of the captopril renogram was compared with that of the captopril test by investigating 34 patients with renal artery stenosis (23 uni-, 11 bilateral) (atherosclerosis: 23, fibromuscular hyperplasia: 11). The captopril renogram was positive more often (n = 12) than the captopril test (n = 4) in patients without renal functional impairment of the stenosed kidney. Similar results were obtained with both methods in patients with atrophic kidneys: captopril renography was positive in all cases with a positive captopril test.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗