Isolated Perfused Kidneys

After the equilibration period, clearance periods of 20 min are used. Urine samples are collected and perfusate is obtained at midpoint of the clearance period for the evaluation of overall kidney function. For determination of glomerular filtration rate (GFR) and fluid transport, 3H-labelled polyethylene glycol is added to a modified Krebs-Henseleit bicarbonate buffer. Electrolytes are determined in urine by standard flame photometry. Fractional excretions of water, electrolytes and test compounds are calculated. 

Tarako et al. (1991) evaluated oxygen supply and energy state in the isolated perfused rat kidney. Metabolic activities of the isolated perfused rat kidney were described by Nishiitsutsuji-Uwo et al. (1967). Cox et al. (1990) used the isolated perfused rat kidney as a tool in the investigation of renal handling and effects of nonsteroidal anti-inflammatory drugs. 

Maack T (1980) Physiological evaluation of the isolated perfused rat kidney. Am J Physiol 238 F71-F78 Newton JF, Hook JB (1981) Isolated perfused rat kidney. Meth Enzymol 77 94-105 

Nishiitsutsuji-Uwo JM, Ross BD, Krebs HA (1967) Metabolic activities of the isolated perfused rat kidney. Biochem J 103 852-862 

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Isolated perfused kidney Isolated tubules Renal cells Cell lines Primary cells Kidney slices Isolated organelles... 

Bekersky, I. (1983). The isolated perfused kidney as a pharmacological tool. TIBS 4 6-7. 

In the isolated perfused kidney model, the artery of the kidney is perfused and urinary samples as well as venous blood samples can be collected to determine the drug concentration. A serious drawback of the model is that isolation and artificial perfusion greatly affect the function of the organ as shown by a dramatic drop in the glomerular filtration rate. Another in-vitro model is the isolated tubule in which samples can be taken from both the luminal and basolateral sites of the tubule [140,141]. The disadvantage of this technique as well as of the isolated kidney model, is that they require specific equipment and expertise and therefore can only be performed in rather specialized laboratories. Experiments using freshly isolated or cultured cells are more simple to carry out [142,143]. Tubular cells can be grown in a po-... 

Because of the kidney s involvement in the excretion of hydrophilic compounds and because most of the substrates of P-gp are hydrophobic compounds that are likely to be cleared mainly by biliary excretion or intestinal secretion, comparably fewer studies have been performed with the isolated perfused kidney. The isolated perfused rat kidney model was used to demonstrate that digoxin is actively secreted by P-gp located on the luminal membrane of renal tubular epithelial cells and that clinically important interactions with qui-nidine and verapamil are caused by the inhibition of P-gp activity in the kidney (332). These results provide an excellent example of how the isolated perfused kidney model can be used to definitively conclude that P-gp-mediated efflux is involved in the renal excretion of a compound and also to elucidate possible DDIs that might arise in the kidney following coadministration of P-gp sub strates/inhibitors. 

The patch clamp technique can be applied to cultured kidney cells (Merot et al. 1988), to freshly isolated kidney cells (Hoyer and Gogelein 1991) or to cells of isolated perfused kidney tubules (Gogelein and Greger 1984). The latter method shall be described in more detail. 

Nizet A (1975) The isolated perfused kidney possibilities, limitations and results. Kidney Int 7 1-11 Pang KS, Cherry WF, Ulm EH (1985) Disposition of enalapril in the perfused rat intestine-liver preparation absorption, metabolism and first-pass effect. J Pharmacol Exp Ther 233 788-795... 

Isolated perfused kidney Morphologically identical to kidney in vivo. Can monitor renal function. Short term use. In the process of degeneration. 

Various animal models have been used to study the pathogenesis of acute kidney injury (AKl) and develop therapeutic interventions that prevent or amehorate the severity of tubular injury following an acute ischemic or toxic renal insult. Utilization of animal models has advantages over other in mtro models such as isolated perfused kidneys, isolated proximal tubules, or tubular cell culture. It reproduces the complex interactions of hemodynamics and local tubular factors seen in the whole animal with AKl. 

Epstein FFI, Brosnan JT, Tange JD, Ross BD Improved function with amino acids in the isolated perfused kidney. Am J Physiol 243 284-92,1982... 

Barac-Nieto M, Gupta RK, Spitzer A NMR studies of phosphate metabolism in the isolated perfused kidney of developing rats. Pediatr Nephrol 4 392-8,1990... 

Endre ZH, Hull WE, Fichtner K-P, Werner U, Kriz W, Ritz E Development of MR Microscopy for the functioning isolated perfused kidney, in Renal Magnetic Resonance Experimental and Clinical Applications, edited by Endre ZH, New York, Marcel Dekker, 2002,... 

Rapacon M, Mieyal P, McGiff JC, Fulton D, Quilley J Contribution of calcium-activated potassium channels to the vasodilator effect of bradykinin in the isolated, perfused kidney of the rat. Br J Pharmacol 118 1504-8,1996... 

Bagate K, Grima M, Imbs JL, Jong WD, Helwig JJ, Barthelmebs M Signal transduction pathways involved in kinin B(2) receptor-mediated vasodilation in the rat isolated perfused kidney. Br J Pharmacol 132 1735-42, 2001... 

Ziyyat A, Zhang BL, Benzoni D Interactions between nitric oxide and prostanoids in isolated perfused kidneys of the rat. Br J Pharmacol 119 388-92,1996... 

Raz E, Kaminski N, Brezis M Effects of perfusion pressure and renal flow upon albumin excretion in isolated perfused kidneys [see comments]. Nephron 56 396-8,1990... 

Lapinski R, Perico N, Remuzzi A, Sangalli E, Benigni A, Remuzzi G Angiotensin II modulates glomerular capillary permselectivity in rat isolated perfused kidney. J Am Soc Nephrol 7 653-60,1996... 

Saunders JR, Aminian A, McRae JL, O Farrell KA, Adam WR, Murphy BF Clusterin depletion enhances immune glomerular injury in the isolated perfused kidney. Kidney Int 45 817-27,1994... 

Isolated perfused kidney/tubule Renal cortical slices Nephron segments Isolated renal epithelial cells Renal cell cultures... 

The isolated perfused kidney allows the investigator the ability to monitor the effects of chemicals on the intact kidney without the effects of extrarenal systems. Transport of chemicals occurs via normal mechanisms as vasculature and tubular lumen remain open in the perfused state, and renal handling and biotransformation of chemicals can be evaluated using this technique. However, to utilize an isolated perfused kidney preparation, a special apparatus must be used. 

Evidence that this subtype is also expressed in human prostate was foimd by Ford et al. [18]. A new O], selective antagonist, RS 17053, demonstrates an approximately 100-fold selectivity in binding at the a,a-AR subtype over the 0, and subtypes (based on studies with both cloned and native subtypes). This compound potently inhibits NE-stimulated contraction of isolated perfused kidney (expressing the o,a-AR subtype) and weakly inhibits the NE stimulated contraction of aortic rings (expressing the oib or Oip-AR subtype), verifying its predictable activity in functional studies. 

The P2X- ntagonism by PPADS has been confirmed in a wide range of tissues and cells including guinea-pig vas deferens [57], rabbit urinary bladder detrusor muscle [28], rabbit blood vessels [29], rat mesenteric arterial bed [30] (Table 3), rat isolated perfused kidney [58], rat sympathetic ganglia [59] and xenopus oocytes injected with RNA transcribed from a P2X cDNA clone from rat vas deferens [17]... 

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