ISSN:1660-8151    

DOI:10.1159/000181416

出版商:S. Karger AG    

年代:1978

数据来源: Karger

ISSN:1660-8151    

DOI:10.1159/000181417

出版商:S. Karger AG    

年代:1978

数据来源: Karger

ISSN:1660-8151    

DOI:10.1159/000181418

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The pathogenesis of sodium retention in many disease states characterized by generalized edema remains incompletely defined, in part due to difficulties which attend experimental maneuvers including perturbation of extracellular fluid volume status. Studies from our laboratory have succeeded in circumventing many of these problems by applying a newly developed investigative tool, the water immersion model, to the assessment of renal function and volume-hormonal relationships in disease states characterized by abnormal volume regulation. The present article reviews the features of the immersion model which commend its application in the assessment of the pathogenesis of sodium retention in a prototypical disease state – decompensated cirrhosis. Furthermore, the demonstration that the central hypervolemia of immersion produces a prompt and profound suppression of plasma renin (PRA) and plasma aldosterone (PA) without concomitant alterations of serum sodium and potassium concentration has allowed the utilization of the immersion model to assess the responsiveness of both PRA and PA in cirrhosis. The experience to date commends the future use of the immersion model as an investigative tool to elucidate further the pathogenesis of many disease states characterized by deranged volume homeostasi

ISSN:1660-8151    

DOI:10.1159/000181419

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

In previous microperfusion studies in the rat, increasing luminal fluid magnesium concentration from 1.5 to 6.0 mEq/1 resulted in a 62% fall in proximal and a 74% fall in distal tubular osmotic water permeability. To determine whether this reduction in rat proximal tubular osmotic water permeability produced osmotic dysequilibrium between proximal tubular fluid and plasma, proximal (TF/P)osm were measured during isotonic saline and magnesium chloride infusion. In 11 rats, proximal (TF/P)osm was 0.99 ± 0.01 during isotonic saline and 0.98 ± 0.01 during magnesium chloride infusion; plasma magnesium concentration increased from 1.76 ± 0.12 to 6.03 ± 0.30 mEq/1. The effect of magnesium on the ability of hydropenic anti-diuretic rats and dogs to reabsorb free water was examined during hypertonic mannitol and saline diuresis. In the rat free water reabsorption was not affected by hypermagnesemia. In the dog hypermagnesemia caused a reduction in free water reabsorption at low levels of solute excretion and formation of a urine hypotonic to plasma at high levels of solute excretion. The reduction in rat proximal and distal tubule osmotic water permeability is not sufficient to affect osmotic equilibration across these tubular segments. Free water reabsorption, reflecting solute reabsorption in the ascending limb of Henle’s loop, is decreased by magnesium in the dog but not in th

ISSN:1660-8151    

DOI:10.1159/000181420

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The intravenous administration of triple typhoid vaccine to anesthetized dogs resulted in a significant increase in renal blood flow accompanied by a modest decline in systemic blood pressure. This renal hyperemia was associated with elevated renal secretory rates of renin and prostaglandin E and F. Measurements of the intracortical distribution of radiolabeled microspheres revealed a progressive decrease in outer cortical blood flow rates and a progressive increase in inner cortical flow rates. When meclofenamate, an inhibitor of prostaglandin synthetase, was administered concomitantly with triple typhoid vaccine renal hyperemia did not develop. The renal renin secretory rate increased modestly and intracortical renal blood flow was not redistributed. The increased renal blood flow after triple typhoid vaccine administration to unanesthetized dogs was also reversed by meclofenamate. The marked increase in prostaglandin secretion by the kidney during renal hyperemia following triple typhoid vaccine administration (pyrogen), and the effect of meclofenamate, is consonant with a role for increased renal synthesis and release of prostaglandins.

ISSN:1660-8151    

DOI:10.1159/000181421

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The role of intratubular obstruction in the pathogenesis of folic acid-induced renal failure was studied. During 3 h following injection of 250 mg/kg i. v. of folic acid in the rat, urine flow was diminished (less than 1 µl/min/100 g), inulin clearance fell below Vioth of the control values, lissamine green passage time through proximal surface tubules was prolonged up to 65 sec and intratubular pressure rose to 40 mm Hg or higher. Folic acid casts could be seen on the cryostat sections in the lumen of the tubules and in the urine. Acute renal failure could be prevented either by massive furosemide diuresis or by alkahnization with small amounts of intravenous NaHCO3. Split oil droplet experiments showed a reduction of the proximal tubular reabsorptive capacity at 2 and at 24 h after folic acid injection. However, a similar impairment was measured after bilateral ureteral ligature at 2 and at 24 h without folic acid. It is concluded that folic acid, because of its poor solubility particularly at an acid pH, precipitates intratubularly as a consequence of fluid reabsorption and increasing acidity along the nephron. Intratubular obstruction due to folic acid crystals thus appears to be the primary cause of acute renal failure induced by folic acid injection. Reduction of proximal tubular reabsorptive capacity is probably due to intratubular obstruction rather than to a direct effect of folic acid on tubular enzyme activity described earlier

ISSN:1660-8151    

DOI:10.1159/000181422

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Na-K-ATPase activity and renal function were compared in rats studied after relief of 24 h of unilateral or bilateral ureteral ligation (UUL or BUL), that is, in the absence or presence of post-obstructive diuresis. Na-K-ATPase activity in the outer medulla of the rat kidney after relief of UUL was not significantly altered immediately but was markedly reduced 1 and 3 days post-obstruction. The decrease in medullary Na-K-ATPase activity was not significantly different from that observed after relief of BUL. These results indicate that decreased Na-K-ATPase activity in the post-obstructive kindney is not responsible for post-obstructive diuresis and is not due to uremia, but is a local phenomenon which is probably secondary to altered renal structure or function. It may be due to decreased filtered sodium load or direct tubular damage, but other data suggests that the decreased medullary solute concentration gradient in the post-obstructive kidney (UUL or BUL) may influence Na-K-ATPase activity which, in turn, contributes to the decreased ability to conserve sodium and water.

ISSN:1660-8151    

DOI:10.1159/000181423

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The small intestinal bacterial flora of 15 patients with chronic renal insufficiency was compared with that of subjects with blind loop syndrome. 9 patients were on regular hemodialysis with high protein intake and 6 (serum creatinine 7.5 to 12.5 mg/dl) were maintained on low protein diet. The chronic renal patients harbored a greatly increased microbial flora of both anaerobes and aerobes in the duodenum and jejunum, quantitatively comparable to those in blind loop subjects. The composition did not differ significantly in the two groups. Some organisms may have the potential to metabolize substrates which reach the intestinal lumen from the diet and bile, and perhaps to generate toxic metabolites that could contribute to uremic toxicity or malabsorption.

ISSN:1660-8151    

DOI:10.1159/000181424

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Recent work from our laboratory on the mechanism of polypeptide hormone handling by the normal kidney and the pathogenesis of altered hormonal metabolism in renal failure is reviewed. The kidney extracts substantial amounts of low – and medium – molecular weight polypeptide hormones from the renal circulation by a process which probably involves both glomerular filtration plus luminal reabsorption and direct peritubular uptake, although the relative contribution of the two mechanisms under physiologic conditions is not known. The bulk of the extracted hormone is catabolized in the renal parenchyma since urinary excretion is negligible. Renal catabolism contributes an important fraction of the total metabolic clearance of polypeptide hormones, which accounts in part for their increased circulating levels in renal failure. Since certain hormones are heterogenous and a large proportion of their plasma immunoreactivity may consist of components of uncertain biologic activity, simple correlations between circulating hormone levels and endocrine abnormalities in uremia are hazard

ISSN:1660-8151    

DOI:10.1159/000181425

出版商:S. Karger AG    

年代:1978

数据来源: Karger