Effect of chronic ethanol consumption on postnatal development of renal (Na + K)-ATPase in the rat

A review on renal toxicity profile of common abusive drugs

Drug abuse has become a major social problem of the modern world and majority of these abusive drugs or their metabolites are excreted through the kidneys and, thus, the renal complications of these drugs are very common. Morphine, heroin, cocaine, nicotine and alcohol are the most commonly abused drugs, and their use is associated with various types of renal toxicity. The renal complications include a wide range of glomerular, interstitial and vascular diseases leading to acute or chronic renal failure. The present review discusses the renal toxicity profile and possible mechanisms of commonly abused drugs including morphine, heroin, cocaine, nicotine, caffeine and alcohol.

Long-lasting neural circuit dysfunction following developmental ethanol exposure

Fetal Alcohol Spectrum Disorder (FASD) is a general diagnosis for those exhibiting long-lasting neurobehavioral and cognitive deficiencies as a result of fetal alcohol exposure. It is among the most common causes of mental deficits today. Those impacted are left to rely on advances in our understanding of the nature of early alcohol-induced disorders toward human therapies. Research findings over the last decade have developed a model where ethanol-induced neurodegeneration impacts early neural circuit development, thereby perpetuating subsequent integration and plasticity in vulnerable brain regions. Here we review our current knowledge of FASD neuropathology based on discoveries of long-lasting neurophysiological effects of acute developmental ethanol exposure in animal models. We discuss the important balance between synaptic excitation and inhibition in normal neural network function, and relate the significance of that balance to human FASD as well as related disease states. Finally, we postulate that excitation/inhibition imbalance caused by early ethanol-induced neurodegeneration results in perturbed local and regional network signaling and therefore neurobehavioral pathology.

Developmental programming of hypertension and kidney disease

A growing body of evidence supports the concept that changes in the intrauterine milieu during "sensitive" periods of embryonic development or in infant diet after birth affect the developing individual, resulting in general health alterations later in life. This phenomenon is referred to as "developmental programming" or "developmental origins of health and disease." The risk of developing late-onset diseases such as hypertension, chronic kidney disease (CKD), obesity or type 2 diabetes is increased in infants born prematurely at <37 weeks of gestation or in low birth weight (LBW) infants weighing <2,500 g at birth. Both genetic and environmental events contribute to the programming of subsequent risks of CKD and hypertension in premature or LBW individuals. A number of observations suggest that susceptibility to subsequent CKD and hypertension in premature or LBW infants is mediated, at least in part, by reduced nephron endowment. The major factors influencing in utero environment that are associated with a low final nephron number include uteroplacental insufficiency, maternal low-protein diet, hyperglycemia, vitamin A deficiency, exposure to or interruption of endogenous glucocorticoids, and ethanol exposure. This paper discusses the effect of premature birth, LBW, intrauterine milieu, and infant feeding on the development of hypertension and renal disease in later life as well as examines the role of the kidney in developmental programming of hypertension and CKD.

Ethanol and hormesis

This article provides a detailed assessment of the toxicological and pharmacological literature concerning alcohol-induced biphasic dose-response relationships. The assessment reveals that alcohol-induced hormetic-like dose-response relationships are commonly observed, highly generalizeable according to model and endpoint and quantitative feature of the dose response. These findings have important implications affecting study design, animal model, and endpoint selection as well as clinical applications.

Alcohol misuse and renal damage

Recent clinical and experimental studies have demonstrated that the habitual consumption of large amounts of ethanol has deleterious effects on the kidney. A variety of tubular defects have been described in patients with chronic alcoholism. Evidence is emerging that tubular dysfunction has an important pathophysiological role in a wide range of electrolyte and acid-base disturbances commonly observed in these patients, and possibly in alcohol-induced bone disease. These renal abnormalities are often reversible, disappearing with abstinence. However, since 1990 a few cases of a syndrome of acute tubular necrosis due to binge drinking of ethanol in the absence of other evident nephrotoxic mechanisms, or in association with the use of nonsteroidal anti-inflammatory drugs, have been reported. A link between glomerulonephritis and alcoholism has become evident. IgA nephropathy has been demonstrated at autopsy in 64% of chronic alcoholics and, more recently, the association between alcoholism and postinfectious glomerulonephritis has been described. Structural and functional abnormalities of the kidney are reported with increasing frequency in the fetal alcohol syndrome seen in children who have been prenatally exposed to ethanol. In addition, over the last few years experimental studies in vitro or in animal models have provided information about the biochemical and molecular basis of alcohol-induced injury to kidney. It is hoped that future experimental and clinical research will provide us with a more comprehensive knowledge of the mechanisms of renal damage in alcohol misuse.

Effect of ethanol on regulation of (Na + K)-adenosine triphosphatase by aldosterone and dexamethasone in cultured renal papillary collecting duct cells

Chronic ethanol exposure causes alterations in biologic membranes of different cell types. (Na + K) adenosine triphosphatase (ATPase), a membrane-bound enzyme inhibited by the acute presence of ethanol, increases its activity in rat kidney after chronic ethanol consumption. The aim of this investigation was to evaluate the effect of ethanol on the modulation of (Na + K)-ATPase by glucocorticoids and mineralocorticoids in renal papillary collecting duct cells. Cultured renal papillary collecting duct cells were exposed to a medium containing 150 mM ethanol plus either 100 nM aldosterone or 10 nM dexamethasone. Control groups were cultured in the absence of ethanol and/or the hormones. Mg(2+)-ATPase was used as control enzyme. The activity of ATPases was measured by ATP hydrolysis. Ethanol increased the activities of (Na + K)-ATPase and Mg(2+)- ATPase in 29 and 33% of controls, respectively; only (Na + K)-ATPase activity was elevated in the presence of aldosterone or dexamethasone, whereas Mg(2+)-ATPase was unaltered by these hormones. The effects of aldosterone and dexamethasone on (Na + K)-ATPase activity were augmented by ethanol in 50 and 19% of controls, respectively. These results suggest that ethanol treatment enhances the upregulation of (Na + K)-ATPase activity by both aldosterone and dexamethasone, in cultured renal papillary collecting duct cells.

Renal damage mediated by oxidative stress: a hypothesis of protective effects of red wine

Over the last decade, oxidative stress has been implicated in the pathogenesis of a wide variety of seemingly unrelated renal diseases. Epidemiological studies have documented an association of moderate wine consumption with a decreased risk of cardiovascular and neurological diseases; however, similar studies in the kidney are still lacking. The kidney is an organ highly vulnerable to damage caused by reactive oxygen species (ROS), likely due to the abundance of polyunsaturated fatty acids in the composition of renal lipids. ROS are involved in the pathogenic mechanism of conditions such as glomerulosclerosis and tubulointerstitial fibrosis. The health benefits of moderate consumption of red wine can be partly attributed to its antioxidant properties. Indeed, the kidney antioxidant defense system is enhanced after chronic exposure to moderate amounts of wine, a response arising from the combined effects of ethanol and the nonalcoholic components, mainly polyphenols. Polyphenols behave as potent ROS scavengers and metal chelators; ethanol, in turn, modulates the activity of antioxidant enzymes. Therefore, a hypothesis that red wine causes a decreased vulnerability of the kidney to the oxidative challenges could be proposed. This view is partly supported by direct evidences indicating that wine and antioxidants isolated from red wine, as well as other antioxidants, significantly attenuate or prevent the oxidative damage to the kidney. The present hypothesis paper provides a collective body of evidence suggesting a protective role of moderate wine consumption against the production and progression of renal diseases, based on the existing concepts on the pathophysiology of kidney injury mediated by oxidative stress.

Changes in (Na + K)-adenosine triphosphatase activity and ultrastructure of lung and kidney associated with oxidative stress induced by acute ethanol intoxication

STUDY AND OBJECTIVES: (Na + K)-adenosine triphosphatase (ATPase) activity, oxidative stress parameters, and morphologic characteristics of the lung and kidney of rats under acute ethanol intoxication were assessed to investigate the pathogenic mechanism of tissue damage.

DESIGN AND INTERVENTIONS

Adult rats were given ethanol (5.5 g/kg) 3 h before performing the biochemical and morphologic studies. Oxidative stress was assessed by measuring the levels of reduced glutathione (GSH) and glutathione disulfide (GSSG), the activities of key antioxidant enzymes (ie, catalase [CAT], superoxide dismutase [SOD], and glutathione peroxidase [GSH-Px]) and malondialdehyde production. (Na + K)-ATPase, a membrane-bound enzyme, also was assayed.

RESULTS

In the lung, ethanol increased MDA production by 60%, decreased GSH levels by 33%, decreased SOD and GSH-Px activity by 10%, and decreased (Na + K)-ATPase activity by 55%, whereas CAT activity was unaltered. Impaired surfactant secretion and cell adhesion of lung epithelial cells were found. In the kidney, ethanol did not influence the activity of (Na + K)-ATPase or lipid peroxidation, despite the reduction of both GSH and the GSH/GSSG ratio. Focally thickened glomerular basement membrane, apoptosis of foot processes, and tubulointerstitial fibrosis were found.

CONCLUSIONS

These data suggest that oxidative stress plays a role in mediating the ethanol-induced down-regulation of lung (Na + K)-ATPase. GSH depletion seems to be a major determinant of this effect. Independent mechanisms seem to account for the morphologic alterations of these organs.

Effects of chronic ethanol consumption on extramitochondrial fatty acid oxidation and ethanol metabolism by rat kidney

1. We evaluated the effects of chronic ethanol consumption on microsomal and peroxisomal fatty acid oxidation and on ethanol oxidation by the kidney. 2. When mature rats were fed 20% ethanol for 10 weeks, an increase in alcohol dehydrogenase and catalase activities were observed in the kidney. 3. Renal microsomal and peroxisomal oxidation of fatty acids also increased by the treatment, but total cytochrome P450 content did not. 4. We concluded that chronic ethanol consumption results in an increased extramitochondrial disposition of fatty acids and ethanol oxidation by the kidney.

Acute and chronic effect of ethanol on (Na + K)-ATPase activity and cyclic AMP response to vasopressin in rat papillary collecting duct cells

1. We evaluated the effects of ethanol on (Na + K)-ATPase activity and cAMP response to vasopressin in native and cultured rat papillary collecting duct (PCD) cells. 2. A significant increase in (Na + K)-ATPase and Mg(2+)-ATPase activities was found in PCD cells either isolated from chronic ethanol-fed rats or cultured in the presence of ethanol. 3. Acute treatment with ethanol resulted in a biphasic effect on the activity of (Na + K)-ATPase, which was enhanced below 1% ethanol and inhibited at higher concentrations. 4. Chronic ethanol treatment did not change the cAMP response of PCD cells to vasopressin. Acutely, in turn, this response was enhanced by ethanol per se. 5. It is suggested that the antinatriuretic effect of ethanol could be at least in part mediated by a (Na + K)-ATPase enhancement in PCD cells. Acutely, ethanol could normalize water balance by its peripheral effects on distal nephron.

Effects of chronic and acute ethanol exposure on renal (Na + K)-ATPase in the rat

1. We evaluated the effects of chronic ethanol consumption on the kinetic properties of renal (Na + K)-ATPase and compared them with acute inhibition by ethanol in vitro. 2. When adult rats were fed 20% ethanol for 10 weeks, renal (Na + K)-ATPase activity increased but the sensitivity of the enzyme to ethanol inhibition in vitro was not altered. 3. Vmax was increased by ethanol consumption, whereas K0.5 and nH were not changed. The kinetic parameters of Mg(2+)-ATPase were not affected under the same conditions. 4. We concluded that ethanol-induced tolerance or enhancement of renal (Na + K)-ATPase or both can be explained on the basis of an increase in Vmax.

Renal tubular dysfunction in chronic alcohol abuse--effects of abstinence

BACKGROUND

Alcohol abuse may be accompanied by a variety of disorders of electrolyte and acid-base metabolism. The role of the kidney in the pathogenesis of these disturbances is obscure. We sought to evaluate the alcohol-induced abnormalities of renal function and improvement during abstinence and to assess the relation between renal dysfunction and electrolyte and acid-base disorders.

METHODS

We measured biochemical constituents of blood and renal function before and after four weeks of abstinence in 61 patients with chronic alcoholism who had little or no liver disease.

RESULTS

On admission, 18 patients (30 percent) had hypophosphatemia and hypomagnesemia, 13 patients (21 percent) had hypocalcemia, and 8 patients (13 percent) had hypokalemia. Twenty-two patients (36 percent) had a variety of simple and mixed acid-base disorders. Twenty of these patients had metabolic acidosis, and among them, 80 percent had alcoholic acidosis. A wide range of defects in renal tubular function, with normal glomerular filtration rate, were detected in these patients. The defects included decreases in the threshold and maximal reabsorptive ability for glucose (38 percent of patients) and in the renal threshold for phosphate excretion (36 percent); increases in the fractional excretion of beta 2-microglobulin (38 percent), uric acid (12 percent), calcium (23 percent), and magnesium (21 percent); and aminoaciduria (38 percent). Seventeen patients (28 percent) had a defect in tubular acidification, and five an impairment in urinary concentrating ability. Urinary excretion of N-acetyl-beta-D-glucosaminidase and alanine aminopeptidase were increased in 41 and 34 percent of patients, respectively. The abnormalities of blood chemistry and renal tubular function disappeared after four weeks of abstinence.

CONCLUSIONS

Transient defects in renal tubular function are common in patients with chronic alcoholism and may contribute to their abnormalities of serum electrolyte and blood acid-base profiles.