Regulation of papillary plasma flow by angiotensin II

Regulation of papillary plasma flow by angiotensin II. We examined in anesthetized dogs the effects of left (L) intrarenal artery infusion of angiotensin II (AII) on renal hemodynamics, urinary concentration and Na excretion, and papillary plasma flow (PPF) (measured by the albumin accumulation technique) in both kidneys. Following AII infusion (0.5 ng/kg/min) into the L renal artery, urinary Na excretion decreased and osmolality increased slightly ipsilaterally, whereas Na excretion did not change significantly and osmolality decreased in the right (R) kidney. PPF was significantly lower in the L compared to the R kidney. When saline loading was superimposed on L intrarenal AII infusion, there was a blunted natriuretic response ipsilaterally with a significantly smaller decrease in urine osmolality compared with the R kidney. PPF increased significantly in the R, but not in the L kidney. Finally, AII blockade with saralasin prior to AII infusion and saline loading prevented the differences between the two kidneys, including PPF. In all groups GFR and renal blood flow did not differ between the two kidneys before or after AII. These data suggest that AII regulates regional blood flow in the medulla, and that the exogenously administered AII induces papillary ischemia, which serves to preserve medullary hypertonicity, preventing an increase in PPF during saline loading, and possibly contributing to the diminished natriuretic response

The effects of angiotensin II on renal water and electrolyte excretion in normal and caval dogs

Abstract. The effects of intravenous administration of angiotensin II on renal water and electrolyte excretion were examined during hydropenia, water diuresis, and hypotonic saline diuresis in anesthetized normal dogs and dogs with thoracic inferior vena cava constriction and ascites (caval dogs). The effects of unilateral renal artery infusion of a subpressor dose were also examined. During hydropenia angiotensin produced a decrease in tubular sodium reabsorption, with a considerably greater natriuresis in caval dogs, and associated with a decrease in free water reabsorption (TCH2o). Water and hypotonic saline diuresis resulted in an augmented angiotensin natriuresis, with a greater effect still observed in caval dogs. In these experiments free water excretion (CH2O) was limited to 8-10% of the glomerular filtration rate (GFR), although distal sodium load increased in every instance. In the renal artery infusion experiments a significant ipsilateral decrease in tubular sodium reabsorption was induced, particularly in caval dogs. These findings indicate that angiotensin has a direct effect on renal sodium reabsorption unrelated to a systemic circulatory alteration. The attenuation or prevention of the falls in GFR and effective renal plasma flow (ERPF) usually induced by angiotensin may partially account for the greater natriuretic response in caval dogs and the augmentation during water or hypotonic saline diuresis. However, a correlation between renal hemodynamics and the degree of natriuresis induced was not always present and, furthermore, GFR and ERPF decreased significantly during the intrarenal artery infusion experiments. Therefore, the present experiments indicate that another mechanism is operative in the control of the angiotensin natriuresis and suggest that alterations in intrarenal hemodynamics may play a role. The decrease in TCHSo and the apparent limitation of CH2O associated with an increase in distal sodium load localize the site of action of angiotensin to the ascending limb of Henle's loop and the proximal tubule. Introduction animals independent of its effect on glomerula

Impact of Achieved Blood Pressure on Cardiovascular Outcomes in the Irbesartan Diabetic Nephropathy Trial

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Aluminum leakage from REDY sorbent cartridge

Although hemodialysis (HD) is able to keep patients with endstage renal disease (ESRD) alive, it does not completely reverse many of the sequellae of chronic renal failure. Hemofiltration (HF) based on convective transport principles similar to that of the natural kidney has been shown to have important advantages over HD. Studies have demonstrated that HF can result in: stabilization of blood pressure during treatment [1]; better control of hypertension between treatments [2]; improvement in uremic symptomatology [3]; improvement in uremic neuropathy [4]. One important drawback to HF as practiced today is the need to replace the large quantities of ultrafiltrate produced by an equal amount of sterile, pyrogen-free electrolyte solution. This procedure is costly and requires precise monitoring to avoid surfeits and deficits. To overcome this major drawback of HF, we examined a method of recycling ultrafiltrate by cleansing it with a sorbent system