Papilla, kidney

Tissue Location and Role of Aldose Reductase in Animal Models of Diabetic Complications. Aldose reductase (AR) has been located immunohistochemically in many tissues of the dog and rat, most notably, in corneal epithelium, retina, optic nerve, kidney papillae, aortic endothelium and smooth muscle cells as well as peripheral nerve and lens. AR has also been measured in human and monkey retinal mural cells. These cells are thought to provide the structural support for retinal capillaries and their loss is the first abnormality seen in clinical diabetic retinopathy. In addition, AR-like activity has been reported in a human retinoblastoma cell line and sorbinil inhibits this activity in these cells. Finally, a recent report has demonstrated that AR is present in isolated capillaries from bovine retina and cerebral cortex. Therefore, AR appears to be present in all tissues which are uniquely susceptible to deterioration during prolonged exposure to the hyperglycemia of diabetes. Accumulation of the products of the polyol pathway, sorbitol and fructose, has been demonstrated in these tissues and, where tested, sorbinil and other AR inhibitors have been shown to inhibit this accumulation. 

An NAD-linked 15-hydroxy-PG dehydrogenase specific for A-type PGs is found in a soluble fraction of rabbit kidney papilla. The enzyme is active with PGA, (K = 15 pM) and PGA2 (K = 6 juM) but neither PGE, PGE2, PGF, , PGF2 or... 

After peroral intake of nickel sulphate in mice, kidney damage appeared at the corticomedullary junction [296]. There was loss of renal tubular epithelial cells and protein loss, giving numerous hyaline casts in the renal tubules and collecting ducts, especially prominent in the renal papillae. 

Examine liver, gallbladder (mouse), stomach, spleen, pancreas, intestines, kidneys, adrenal gland, ureters, bladder, umbilical artery, genital organs, dorsal aorta, and caudal vena cava. Possible abnormalities that can be observed include absent renal papilla, dilated ureter(s), and displaced testis. 

Pentachloroethane given to rats by gavage during a two-year study caused chronic, diffuse kidney inflammation and renal papilla mineralization. A single dose also reduced hepatic cytochrome P450 content and microsomal epoxide hydrolase activities. Inhalation exposure of rabbits to pentachloroethane decreased their total antibody titres (lARC, 1986). 

The renal system consists of the kidneys and their vasculature and innervation, the kidneys each draining through a ureter into a single median urinary bladder, and the latter draining to the exterior via a single duct, the urethra. The kidney has three major anatomical areas the cortex, the medulla, and the papilla. 

The relevance of the kidney effects observed in the dietary studies in rats and mice is unclear because some of the findings (Crocker et al. 1988 David et al. 2000a, 2000b) indicate that they likely reflect exacerbation of age-, species-, and/or sex-related lesions by DEHP and are not accompanied by changes in kidney function. The mechanism of the effect induced by the lowest dietary dose of DEHP (i.e., mineralization of the renal papilla in rats exposed to 5.8 mg/kg/day) is unclear and might be consistent with male rat-specific precipitation of os -globulin (David et al. 2000a). Based on the available data, the kidneys do not demonstrate a consistent response to DEHP. 

These findings from special renal studies and the clinical trial data indicate that inhibition of Cox-2 does not eliminate the renal effects of NSAIDs because Cox-2-derived prostanoids are involved in normal renal function. However, the kidney contains considerably more Cox-1 than Cox-2, and the localization of the two isoforms is different It is not yet known whether the Cox-2 inhibitors will be safer in subgroups of patients prone to develop acute renal failure with NSAIDs, such as those patients with severe volume depletion, congestive heart failure, or hepatic cirrhosis with ascites (Bosch-Marce et al., 1999). Also, it is not known whether rare events, such as interstitial nephritis or papillary necrosis, will occur with long-term use of Cox-2 inhibitors, although studies in animals suggest that such events may be related to Cox-1 inhibition, since only Cox-1 is found in the papilla. Therefore, Cox-2 inhibitors may not produce these serious adverse effects (Khan etal., 1998). 

Upon gross examination, three major anatomical areas of the kidney are apparent cortex, medulla, and papilla (Figure 29.1). The cortex is the outermost portion of the kidney and contains proximal and distal tubules, glomeruli, and peritubular capillaries. Cortical blood flow is high relative to cortical volume and oxygen consumption the cortex receives about 90% of total renal blood flow. A blood-borne toxicant will be delivered preferentially to the renal cortex and therefore has a greater potential to influence cortical, rather than medullary or papillary, functions. 

The papilla is the smallest anatomical portion of the kidney. Papillary tissue consists primarily of terminal portions of the collecting duct system and the vasa recta. Papillary blood flow is low relative to cortex and medulla less than 1% of total renal blood flow reaches the papilla. However, tubular fluid is maximally concentrated and the volume of luminal fluid is maximally reduced within the papilla. Potential toxicants trapped in tubular lumens may attain extremely high concentrations within the papilla during the process of urinary concentration. High intraluminal concentrations of potential toxicants may result in diffusion of these chemicals into papillary tubular epithelial and/or interstitial cells, leading to cellular injury. 

Karlsson KA, Samuelsson BE, Steen GO (1968) Structure and function of sphi-nolipids. 1. Differences in sphingolipid long-chain base pattern between kidney cortex, medulla, and papillae. Acta Chem Scand 22 1361-1364... 

Blood flow to the two kidneys is approximately 22-25% of the cardiac output. The kidneys are supplied by the renal artery which enters the kidneys through the hilum and then branches progressively to form the interlobar arteries, arcuate arteries, interlobular arteries (also called radial arteries), and afferent arterioles, which lead to the glomerular capillaries. The distal ends of each glomerulus coalesce to form the efferent arteriole, which leads to a secondary capillary network, the peritubular capillaries which surround the renal tubules. The cortex receives approximately 90% of the blood flow compared to the medulla or papillae so blood-borne toxic molecules reaching the kidneys have a more toxic effect on the cortex, as compared to the medulla or renal papillae. The interstitial space is occupied by the fenestrated peritubular capillaries and a small number of fibroblast-like cells. Increase in thickness of interstitial space in pathological conditions is due to edema, proliferation of fibrous tissue, or infiltration of inflammatory cells (Guyton and Hall, 2006). 

The toxic effect of many xenobiotic compounds in the kidneys is specific to the anatomical locations, i.e. proximal tubules, glomeruli, medulla/papilla, or loop of Henle. The site-selective injury observed in humans when exposed to many compounds is similar to that in domestic animals. The cause of these site-specific target injuries is multifactorial and may include detoxification mechanisms, regenerative ability, difference in blood flow, and transport and accumulation of the chemicals and their metabolites. 

Sour taste detects acids, i.e., protons. Several different sour taste receptor candidates such as acid-sensing ion channels (ASICs) (57), hyperpolarization-activated cyclic nucleotide-gated channels (HCNs) (58), and two pore domain potassium channels (K2PS) (59, 60) have been described in the past. In addition, recent research identified two members of the polycystic kidney disease (PKD) family of the transient receptor potential superfamily (TRP) as strong sour taste receptor candidates or as part thereof. Immunohistochemistry and in situ hybridization revealed the presence of the polycystic-kidney-disease-like ion channel PKD2L1 in subsets of taste receptor cells of mouse fungiform, vallate, and foliate papillae. These cells differ from... 

By definition, papillary necrosis represents the development of irreversible damage within the parenchyma of the renal papillae. The papillae of the kidney contain the tip portions of the long loops of Henle, together with the terminal portions of the collecting duct complexes, which open in to the minor calyces. The minor calyces of the kidneys representing the first location in the upper renal outflow tract into which mine is collected before it travels into the renal pelvis and into the urinary bladder via the ureters. 

Oliver JA et al (2004) The renal papilla is a niche for adult kidney stem cells. J Clin Invest 114(6) 795-804... 

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