Biomedical subjects

B A Molitoris

Publications and source records attributed to B A Molitoris.

At least 37 records · Page 2Linked to original sources

PubMed1997

Cellular mechanism of aminoglycoside tolerance in long-term gentamicin treatment.

In the rat, nephrotoxicity results from uptake of gentamicin at the apical membrane of proximal tubule (PT) cells. However, during continuous gentamicin treatment, the PT epithelium has been shown to recover. The mechanism(s) of cellular recovery and development of tolerance remains unknown. Therefore, we undertook studies designed to characterize cellular adaptations that occur during long-term gentamicin (LTG) treatment. After 19 days of gentamicin treatment, electron microscopy morphological evaluation revealed cellular recovery with an apparent mild decrease in height and number of microvilli. Enzymatic analysis of LTG PT membranes showed that apical and basolateral membranes had essentially returned to normal. Analysis of apical membrane lipid content revealed persistent statistically significant (P < 0.01) elevations in phosphatidylinositol (PI). In vivo immunogold morphological studies and biochemical studies in LTG rats revealed that endocytosis of gentamicin was selectively reduced, whereas the markers of fluid-phase (horseradish peroxidase) and receptor-mediated (beta2-microglobulin) endocytoses were unaffected or increased. Biochemical analysis showed that, although gentamicin binding to apical membranes isolated from LTG rats increased greater than twofold (P < 0.05) over membranes from untreated rats, in vivo cellular uptake, quantified with [3H]gentamicin, was reduced. Western blot analysis of LTG apical membranes and immunofluorescent staining of perfusion-fixed LTG kidneys showed no change in megalin levels or its apical membrane localization. These data imply that recovery of PT cells from and tolerance to LTG treatment involve a selective inhibition of gentamicin uptake across the apical membrane. They indicate that the mediators of gentamicin endocytosis were affected differently: PI levels increased, whereas megalin levels did not change. We conclude that selective inhibition of gentamicin uptake during LTG treatment is not affected by a reduction in PI or megalin levels. We postulate that trafficking of gentamicin and/or gentamicin-containing endocytic structures is reduced in LTG rats, allowing cells to develop tolerance to gentamicin.

Adaptation, Physiological↗

PubMed1997

ATP depletion alters myosin I beta cellular location in LLC-PK1 cells.

The brush border (BB) of the proximal tubule cell (PTC) requires dynamic membrane events for function. The actin cytoskeleton is necessary for structure and function in this region. ATP depletion disrupts both structure and function. In this report, myosin 1 beta location in LLC-PK1 cells was followed during ATP depletion and repletion using immunofluorescence and Western blot techniques. Myosin I beta colocalized with F-actin in the microvilli and cell periphery, but no colocalization was observed with stress fibers. ATP depletion increased the apical F-actin, and myosin I beta was colocalized there. In addition, after ATP depletion, myosin I beta was extracted less by Triton X-100. These changes were reversed after ATP repletion. Finally, immunofluorescence of kidney sections shows myosin I beta in the BB. These results place this motor in a dynamic region of the PTC where its actin and membrane binding domains can contribute to PTC function.

Actins↗

PubMed1997

Putting the actin cytoskeleton into perspective: pathophysiology of ischemic alterations.

The actin cytoskeleton plays an ever-increasingly understood role in mediating a myriad of processes necessary for cellular structure and function. New and exciting information regarding the dynamic aspects of the actin cytoskeleton and its intracellular regulation are unfolding at a rapid rate. Actin cytoskeletal-surface membrane interactions mediating such diverse cellular events as cell polarity, endocytosis, exocytosis, cell division, cellular migration, cell adhesion, signal transduction, and ion channel activity are part of an ever-growing list of cellular processes dependent on precise actin polarization and regulation of assembly and disassembly. The purpose of this review is to highlight recent advances in the understanding of actin cytoskeleton-mediated cellular processes, to provide a framework that interrelates the complex protein-protein interactions necessary for localization, regulation, and mediation of these essential cellular functions, and to outline the role of actin effector proteins in the pathophysiology of ischemic cell injury.

Actins↗

PubMed1996

Surface membrane polarity of proximal tubular cells: alterations as a basis for malfunction.

The surface membrane of proximal tubular cells is organized into distinct apical and basolateral membrane domains. The establishment and maintenance of these biochemically, structurally and physiologically distinct domains involves a multi-stage process involving cell-cell, cell-ECM interactions, and polarized targeting mechanisms. Ischemia, via cellular ATP depletion, results in a series of structural, biochemical and functional alterations that lead to loss of proximal tubular cell surface membrane polarity. Of central importance is the rapidly-occurring, duration-dependent disruption and dissociation of the actin cytoskeleton and associated surface membrane structures. This results in numerous cellular alterations including loss of cell-cell contact, cell-extracellular matrix adhesion and surface membrane polarity. Redistribution of surface membrane proteins and lipids into the alternate domain results in the cells inability to function properly. Repair of these disorders involves re-establishment of the actin cytoskeleton and apical and basolateral surface membrane domains. Recent information indicates growth factors may play a role in hastening this repair process.

Animals↗

PubMed1996

Cellular ATP depletion induces disruption of the spectrin cytoskeletal network.

Ischemia in vivo or ATP depletion in vitro result in disruption and cellular redistribution of the cortical F-actin cytoskeleton in epithelial cells. However, little is known regarding the effect of these two maneuvers on other components of the actin cytoskeleton. Because the spectrin (fodrin in epithelial cells)-based network links the actin cytoskeleton to the surface membrane, we have utilized a reversible model of ATP depletion in LLC-PK1 cells to study the effect of ATP depletion on fodrin and ankyrin. Under physiological conditions, both ankyrin and fodrin were largely Triton X-100 insoluble and colocalized immunofluorescently along the lateral membranes of LLC-PK1 cells. After ATP depletion, there was a rapid and duration-dependent increase in Triton X-100 solubility of both proteins. This was not true for villin and myosin 1, as Triton X-100 solubility was unaffected and reduced by ATP depletion, respectively. The increase in fodrin and ankyrin detergent solubility during ATP depletion was associated with cytosolic redistribution of the proteins, as determined using immunofluorescent techniques. Sucrose gradient fractionation and Western blot analysis of the Triton X-100-soluble fraction following ATP depletion revealed lack of association between fodrin and ankyrin. Furthermore, dual-label digital confocal immunofluorescent studies revealed lack of association of cytoplasmic ankyrin and fodrin following ATP depletion. Taken together, these data indicate that ATP depletion in LLC-PK1 cells leads to dissociation of both ankyrin and fodrin from the actin cytoskeleton. Furthermore, the two proteins dissociate from each other and redistribute throughout the cytoplasm.

Actins↗

PubMed1995

Plasma protein adsorption to highly permeable hemodialysis membranes.

Although membrane adsorption of plasma proteins is one of several factors determining the biocompatibility and mass transfer characteristics of a hemodialyzer, this process has not been evaluated rigorously. We performed an equilibrium and kinetic analysis of the binding of proteins of differing molecular weight to highly permeable membranes of differing hydrophobicity and surface change. Hydrophobic, anionic polyacrylonitrile (PAN) and hydrophilic, uncharged cellulose triacetate (CT) membrane fragments were incubated in buffer containing radioiodinated beta 2-microglobulin (beta 2m) or bovine serum albumin (BSA). From an initial solution concentration of 50 mg/liter, both membranes adsorbed significantly more beta 2m than BSA at equilibrium (PAN, 352 +/- 30 vs. 32.1 +/- 2.4 ng; CT, 87.0 +/- 0.6 vs. 30.8 +/- 1.7 ng). These results were consistent with membrane pore exclusion of BSA. Comparison of the slopes of the equilibrium isotherm lines (concentration range, 0 to 220 mg/liter) showed the PAN binding affinity for beta 2m and BSA was 28 and 1.4 times that of CT, respectively. In kinetic studies, the approach to equilibrium versus (time)1/2 was assessed. For all protein-membrane combinations, this relationship was linear, consistent with a diffusion-controlled process. This latter characteristic permitted the determination of beta 2m membrane diffusivity values for both PAN and CT, which were found to be 0.30 and 3.25 x 10(-7) cm2/sec, respectively. These data suggest membrane hydrophobicity more significantly influences the binding of low-molecular weight proteins than that of pore-excluded proteins. In addition, these results demonstrate electrostatic membrane-protein interactions may influence the kinetics of both the adsorption and transmembrane mass transfer of plasma proteins.

Adsorption↗

PubMed1995

Convergence of apical and basolateral endocytic pathways for beta 2-microglobulin in LLC-PK1 cells.

Polarized epithelial cells internalize molecules from both apical and basolateral (BL) plasma membrane (PM) domains via receptor-mediated endocytosis. In the kidney, low-molecular-weight proteins (LMWP) are internalized across the apical membrane of proximal tubule cells and degraded in lysosomes. Although indirect evidence suggests some uptake may occur at the BL surface, in vivo studies performed in rats suggest little if any LMWP uptake occurs at the BL surface. The studies presented here showed that native human beta 2-microglobulin (beta 2M) was internalized across the apical surface and followed the same intracellular pathway in the proximal tubule-derived cell line LLC-PK1 as that described in vivo. Either 125I- or gold-labeled beta 2M (125I-beta 2M and gold-beta 2M) bound specifically and reversibly to the apical surface of confluent LLC-PK1 cells. These results were qualitatively similar to previously documented in vivo results. Subsequently, using gold-beta 2M and LLC-PK1 cells grown on porous supports, we showed that a functional uptake system for the LMWP beta 2M was present at the BL surface. Finally, using different-size gold particles conjugated to beta 2M applied simultaneously to the apical and BL surfaces, we observed that apical and BL endocytic routes converged in multivesicular acid phosphatase-negative endosomal structures. Taken together, these data imply that beta 2M can be internalized across both apical and BL domains and that the two pathways converge at a multivesicular level within the endosomal pathway.

Animals↗

PubMed1995

HWA-448 reduces gentamicin toxicity in LLC-PK1 cells.

An LLC-PK1 cell culture model was used to evaluate for a direct protective effect of the pentoxifylline analogue HWA-448 in gentamicin nephrotoxicity at the cellular level. Cells exposed to 2 mM gentamicin for 6 days displayed a significant decrease in specific activities of leucine aminopeptidase, NaK ATPase, and N-acetyl glucosaminidase, and an increase in total cellular phospholipids (P < .05). Concomitant exposure to 0.125 mM HWA-448, a dose that did not alter cellular enzymes or total phospholipids under physiologic conditions, prevented the alterations in marker enzymes and total phospholipids induced by gentamicin (P < .05). Gentamicin binding and uptake studies revealed 0.125 mM HWA-448 had no effect on LLC-PK1 cell plasma membrane binding or cellular gentamicin uptake. We conclude that HWA-448 ameliorates gentamicin-induced alterations in LLC-PK1 cell enzymes and phospholipids by a mechanism independent of plasma membrane binding or cellular uptake.

Animals↗

PubMed1994

Alterations in epithelial polarity and the pathogenesis of disease states.

The establishment and maintenance of epithelial-cell polarity are prerequisites for normal epithelial-cell and organ function. Knowledge of the processes involved in cell polarity has provided insight into the mechanisms of cell dysfunction and the pathogenesis of several diseases. These insights should lead to the development of specific strategies aimed at preventing or minimizing the progression of these diseases.

Cell Membrane↗

PubMed1994

Inherited diseases of the glomerular basement membrane.

The inherited diseases of the glomerular basement membrane include Alport's syndrome (AS), nail-patella syndrome, and thin basement membrane nephropathy. Classical AS is inherited in an X-linked manner and accounts for approximately 85% of the cases. Its manifestations include hematuria, sensorineural hearing loss, ocular defects, and a progression to renal failure. A defect(s) in the alpha 5 (IV) chain of type IV collagen is believed to be the etiology of classic AS, and alterations in its encoding gene localized to the X-chromosome have been elucidated. Although isolated cases of anti-glomerular basement membrane glomerulonephritis have been reported following renal transplantation in patients with AS, it is considered an effective form of renal replacement therapy. Less is known regarding the genetic basis of the autosomal-dominant form of AS, which apparently accounts for the remaining 15% of the cases. Nail-patella syndrome is characterized by nail dysplasia, patellar hypoplasia or aplasia, and nephropathy. It is inherited in an autosomal-dominant fashion with the gene locus assigned to the long arm of chromosome 9. Possible linkage between the COL5A1 gene and the gene for nail-patella syndrome has been suggested. Approximately 30% of the patients progress to end-stage renal failure. Renal transplantation has been successful in treating patients who progress to end-stage renal failure. Thin basement membrane nephropathy is an autosomal dominant trait that accounts for approximately 30% of the cases presenting as persistent, asymptomatic hematuria. The cause of thin basement membrane nephropathy is unknown at present. No decline in renal function is associated with thin basement membrane nephropathy.

Adolescent↗

PubMed1994

Membrane adsorption of beta 2-microglobulin: equilibrium and kinetic characterization.

Enhanced extracorporeal removal of beta 2-microglobulin (beta 2m) may prevent the development of dialysis-related amyloidosis (DRA). One mechanism of beta 2m removal is membrane adsorption. Therefore, we fundamentally characterized beta 2m adsorption to the highly permeable polyacrylonitrile (PAN) membrane. Porous and nonporous PAN fragments were incubated in buffer containing 125I-beta 2m. Over a concentration range of 8 to 60 mg/liter, the equilibrium adsorption isotherm was linear (r = 0.99) for porous PAN while the isotherm for nonporous PAN suggested either multilayer binding or adsorption of proteins with differing orientations. In kinetic analyses, the approach to equilibrium versus (time)1/2 was evaluated. For both porous and nonporous PAN, this relationship was linear (r = 0.99), consistent with a diffusion-controlled process. Adsorption reversibility was assessed by comparing the amount bound at varying residence times (0 to 4 hr) to the amount remaining adsorbed after a subsequent incubation in buffer. The fractions remaining bound at 60, 120, and 240 minutes (0.34 +/- 0.02, 0.36 +/- 0.06, and 0.44 +/- 0.03; mean +/- SEM) were significantly greater (P < 0.05) than the value at five minutes (0.23 +/- 0.01). This suggests membrane-induced conformational changes in adsorbed beta 2m. This investigation permits the comparison of beta 2m adsorptive properties of PAN to those of other membrane-based and nonmembrane-based therapies designed to prevent DRA.

Acrylic Resins↗

PubMed1994

Apically and basolaterally internalized aminoglycosides colocalize in LLC-PK1 lysosomes and alter cell function.

Aminoglycosides bind to apical and basolateral (BL) membranes of renal epithelial cells. However, little is known regarding differential uptake and intracellular processing after internalization across these distinct surface membrane domains. To examine these processes independently, LLC-PK1 cells were grown on porous filters, which allow selective access to both domains. Apical and BL membrane uptakes of gentamicin (0.5 mM), quantified using [3H]gentamicin, were linear from 2 to 24 h (r = 0.99). The 4-h apical gentamicin uptake was 667 +/- 59 pmol/mg protein, the BL 748 +/- 26 pmol/mg protein, and concurrent apical and BL uptake 1,389 +/- 22 pmol/mg protein. Aminoglycoside uptake, documented using indirect immunogold techniques, occurred via the apical and BL endocytic systems and colocalized with cationic ferritin. Aminoglycosides internalized via the apical (gentamicin) and BL (tobramycin) membrane converged at the lysosomal level. Gentamicin incorporated via either domain significantly decreased lysosomal N-acetylglucosaminidase below control values (P < 0.05). We conclude that, after binding, aminoglycosides are internalized equally across apical and BL membranes of LLC-PK1 cells via receptor-mediated endocytosis, colocalize within the lysosomal compartment, and alter cellular function similarly.

Aminoglycosides↗

PubMed1994

Characterization of the beta 2-microglobulin endocytic pathway in rat proximal tubule cells.

The uptake mechanism(s) of low-molecular-weight proteins by proximal tubule cells remains incompletely characterized. We utilized a biochemical and semiquantitative morphological approach to better characterize the endocytic pathway of an anionic protein, beta 2-microglobulin (beta 2M), in the rat proximal tubule. Indirect immunogold techniques revealed beta 2M was taken up via a classic receptor-mediated endocytic pathway. In vitro biochemical and morphological characterization of iodinated beta 2M and gold-conjugated beta 2M (gold-beta 2M) binding to isolated brush-border membrane vesicles (BBMV) documented specific and quantitatively similar binding interactions of the modified beta 2M with BBMV. Kinetic characterization of the in vivo endocytic pathway of gold-beta 2M was undertaken using microinfusion of individual tubules. beta 2M initially bound at the apical surface, was internalized into subapical coated vesicles and delivered to endosomal-like structures within 5 min, and, finally, was concentrated in lysosomal-like structures within 15 min. This uptake was inhibited by excess unconjugated beta 2M. In addition, we directly showed that uptake did not occur across the basolateral surface. Finally, by passing solubilized BBMV over beta 2M affinity columns we were able to isolate binding activity.

Animals↗

PubMed1994

Extracellular acidosis minimizes actin cytoskeletal alterations during ATP depletion.

Extracellular acidosis has been shown to be protective during ischemia in renal tubule cells. However, the mechanism of protection remains unknown. Since ischemia leads to disruption and polymerization of the cortical actin cytoskeleton, we hypothesized acidosis may better preserve the actin cytoskeleton during ischemia. Therefore, the purpose of our studies was to examine the effect of pH on the integrity of the actin cytoskeleton during ATP depletion and ATP repletion. To do this, we used an in vitro model of reversible ATP depletion in LLC-PK1 cells at extracellular pH values (pHo) of 6.9, 7.4, and 7.9. Immunofluorescent studies with rhodamine-phalloidin demonstrated more marked redistribution and clumping of cortical actin at pHo 7.9 and 7.4 vs. 6.9 after 90 min of chemical anoxia. After 15 min of ATP depletion, G-actin, quantified by the deoxyribonuclease assay, decreased from 53.7 +/- 0.8 to 43.2 +/- 1.5 microgram/mg protein at pHo 6.9 vs. 37.6 +/- 1.8 microgram/mg protein at pHo 7.4 (P < 0.001). After 60 min, there still was significantly less conversion of G-actin to F-actin at pHo 6.9 vs. 7.4, with a decrease from 55.9 +/- 2.0 to 39.6 +/- 2.0 micrograms/mg protein at 6.9 vs. 35.8 +/- 2.4 at 7.4 micrograms/mg protein (P < 0.05). Furthermore, extracellular acidosis during the phase of ATP repletion resulted in more rapid normalization of cellular G-actin levels (95 +/- 3% of control vs. 82 +/- 2% for pH 6.9 vs. 7.4, respectively, P < 0.01). Together, these findings indicate the actin cytoskeleton is better preserved in an acidic environment during ATP depletion.(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis↗

PubMed1993

Disease processes in epithelia: the role of the actin cytoskeleton and altered surface membrane polarity.

The establishment and maintenance of cell polarity is essential for normal epithelial function. Disruption of the underlying processes, either as a primary inborn defect or as a secondary result of other pathologic processes, can lead to loss of epithelial polarity and further cellular and organ-level dysfunction. Continued elucidation of the processes involved may prove fruitful both in the understanding of basic cell biology and in the understanding and treatment of a variety of disease states.

Actins↗

PubMed1993

Mechanism of ischemia-enhanced aminoglycoside binding and uptake by proximal tubule cells.

Preceding ischemia or concurrent hypotension is known to enhance aminoglycoside nephrotoxicity; however, the underlying mechanisms responsible have not been determined. To investigate the effect of preceding mild ischemia on cellular gentamicin handling, brush-border membrane vesicle binding and in vivo cellular gentamicin uptake were quantified using [3H]gentamicin as a tracer. Fifteen minutes of ischemia resulted in a marked increase in apical membrane gentamicin binding (2.8 +/- 0.4 vs. 4.9 +/- 0.8 nmol/mg protein, P < 0.01). This increase was associated with an increased number of binding sites (3.7 +/- 0.3 vs. 9.1 +/- 2.3 nmol/mg protein, P < 0.01) and a reduced binding affinity (11.8 +/- 2.2 vs. 27.7 +/- 10.4 microM, P < 0.01). This increase in gentamicin binding was accompanied by alterations in apical membrane phospholipids including a doubling of phosphatidylinositol (PI) levels (13.8 +/- 0.4 vs. 27.5 +/- 3.1 nmol/mg protein, P < 0.01). Furthermore, treatment of apical membrane vesicles with PI-specific phospholipase C markedly reduced the difference in gentamicin binding between paired control and ischemic membrane fractions. Increased gentamicin binding was associated with increased in vivo uptake of gentamicin by S1/S2 and S3 cells. Outer cortical uptake of gentamicin increased from 2.18 +/- 0.39 to 2.68 +/- 0.27 nmol/mg protein (P < 0.01) after 15 min of ischemia and 4 h of reperfusion. Juxtamedullary uptake also increased from 1.39 +/- 0.31 to 1.75 +/- 0.12 nmol/mg protein (P < 0.01). Immunocytochemical techniques, utilizing immunogold labeling, showed gentamicin was taken up via the receptor-mediated endocytic pathway by S1/S2 and S3 cells. After ischemic injury gentamicin was localized in abnormal intracellular accumulations in S3 but not S1 or S2 cells. Taken together, these data indicate ischemia results in a marked increase in apical gentamicin binding due to increases in apical PI content. This is associated with increased internalization by S1/S2 and S3 cells and abnormal intracellular compartmentalization of gentamicin within S3 cells.

Aminoglycosides↗

PubMed1993

Na(+)-K(+)-ATPase that redistributes to apical membrane during ATP depletion remains functional.

We have previously demonstrated using immunocytochemical, histochemical, and biochemical techniques that ischemia in vivo and ATP depletion in vitro result in dissociation of Na(+)-K(+)-adenosinetriphosphatase (ATPase) from the actin cytoskeleton and redistribution to the apical domain in renal proximal tubule cells. To directly evaluate whether apical Na(+)-K(+)-ATPase retained Na+ pumping activity, a rapidly reversible model of cellular ATP depletion in confluent LLC-PK1 cells grown on semipermeable membranes was utilized. Tight-junction integrity, monitored by electrical resistance, was lost during ATP depletion and reestablished during 2 h of ATP repletion. Total cellular Na(+)-K(+)-ATPase activity and total surface membrane [3H]ouabain binding remained constant, but specific apical [3H]ouabain binding increased (7 vs. 26 fmol/filter, P < 0.01). Apical [3H]ouabain binding returned to baseline during 5 h of ATP repletion. Apically applied ouabain was then used to selectively inhibit apical Na(+)-K(+)-ATPase. It had no effect on apical-to-basolateral Na+ flux under physiological conditions (1.3 +/- 0.61 vs. 1.27 +/- 0.46 meq.filter-1.30 min-1), but it increased the apical-to-basolateral flux in ATP-depleted and then repleted monolayers (0.39 +/- 0.12 vs. 0.83 +/- 0.27 meq.filter-1.30 min-1, P < 0.01), implying that apical Na(+)-K(+)-ATPase retained Na+ pumping activity. Together, these data imply that ATP depletion induces loss of surface membrane polarity resulting in redistribution of functional proteins to the alternate domain.

Adenosine Triphosphate↗

PubMed1992

Cytoskeleton disruption and apical redistribution of proximal tubule Na(+)-K(+)-ATPase during ischemia.

The polar distribution of Na(+)-K(+)-ATPase to the basolateral membrane of proximal tubule cells is essential for the efficient and vectorial reabsorption of Na+ and may be dependent on the formation of a metabolically stable, detergent-insoluble complex of Na(+)-K(+)-ATPase with the actin membrane cytoskeleton. The present studies utilized immunocytochemical techniques to demonstrate and quantify the apical redistribution of Na(+)-K(+)-ATPase during mild ischemia (15 min) that occurred in proximal (1.3 +/- 0.9 vs. 4.5 +/- 1.1 particles/100 microns surface membrane, P less than 0.01) but not distal tubule cells. Treatment of control apical membranes with 2-(2-methoxyethoxy)ethyl 8-(cis-2-n-octylcyclopropyl)octanoate (A2C), a fluidizing agent, markedly increased membrane fluidity without any effect on Na(+)-K(+)-ATPase activity. In brush-border membrane vesicles isolated after ischemia, however, A2C further increased an already elevated Na(+)-K(+)-ATPase activity. During ischemia, total cellular Na(+)-K(+)-ATPase activity remained unaltered, but the Triton X-100-soluble (noncytoskeleton associated) fraction of Na(+)-K(+)-ATPase increased significantly following 15 and 30 min. There was a corresponding decrease in the Triton X-100-insoluble fraction of Na(+)-K(+)-ATPase, with the ratio of detergent-soluble to -insoluble Na(+)-K(+)-ATPase increasing from 13 +/- 2 to 32 +/- 5% (P less than 0.01) during 30 min of ischemia. Western blot analysis of the Triton X-100-soluble fraction, following 30 min of ischemic injury, revealed the presence of Na(+)-K(+)-ATPase, actin, fodrin, and uvomorulin. However, in a fraction highly enriched for Na(+)-K(+)-ATPase, neither actin, fodrin, nor uvomorulin was detected.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗