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At least 973 records · Page 54Linked to original sources
PubMed1991

Route of access of secretin into rabbit duodenal lumen during acid perfusion.

The route of entry of immunoreactive secretin into the duodenal lumen during acid perfusion is unknown. Possible sites include paracellular diffusion from the extracellular space, transapical secretion from S cells, or leaching from cells damaged by the perfusate. Antisecretin in the extracellular space and interstitium should reduce access due to paracellular diffusion from the interstitium without significantly affecting secretion or leaching. We therefore studied the effect of intravenous antisecretin antibody on luminal secretin output. Two groups of rabbits received either intravenous normal rabbit serum (controls) or antisecretin antibody, before perfusing a closed segment of duodenum with hydrochloric acid. Preliminary experiments established that duodenal perfusion with HCl concentrations below 0.025N produced no apparent mucosal damage on electron microscopy. HCl concentrations above this significantly damaged the mucosa. In the control group, perfusion with 0.01N, 0.0125N, and 0.025N hydrochloric acid resulted in a dose-dependent increase in secretin in the perfusate. Secretin output was markedly reduced in the group injected with secretin antibody. Antisecretin antibody significantly reduced bile flow at all levels of HCl concentration in the duodenal perfusate. These data suggest that luminal secretin is probably derived from the interstitium and travels to the lumen across narrow paracellular channels.

Animals↗
PubMed1990

Morphological and cytogenetic studies of a human synovial sarcoma xenotransplanted into nude mice.

Specimens of a synovial sarcoma from the left thigh of a 60-year-old woman and cells from the tumor transplanted into nude mice were examined morphologically and immunohistochemically, and the karyotype was analyzed. Immunohistochemically, cells of both the parent tumor and the transplanted tumor were positive for vimentin and cytokeratin. The multicystic features of the parent tumor were not reproduced in the mice. On ultrastructural examination, the parent tumor cells were found to have dilated channels of endoplasmic reticulum as well as a junctional apparatus, and they formed extracellular spaces. The transplanted tumor cells, in contrast, had a poorly developed endoplasmic reticulum and were devoid of extracellular spaces. Chromosome analysis of the tumor cells revealed a translocation, t (X; 18) (p11; q11), as reported previously for synovial sarcoma, thus suggesting the diagnostic utility of the chromosome pattern for identification of synovial sarcoma.

Animals↗
PubMed1970

Diffusion and distribution of dimethyl sulphoxide in the isolated guinea-pig taenia coli.

1. The diffusion of the cryoprotective non-electrolyte dimethyl sulphoxide (DMSO) in the isolated guinea-pig taenia coli at 37, 25 and 0 degrees C has been studied using [(35)S]DMSO.2. Within 1 hr after immersion at 37 degrees C in Krebs solution containing 20% (w/v) DMSO and trace amounts of [(35)S]DMSO, the non-electrolyte was distributed uniformly throughout a volume equivalent to the total initial water content of the muscle.3. The kinetics of efflux of [(35)S]DMSO from muscles at constant volume were analysed on the basis of two models: one incorporated radial diffusion in extracellular fluid with simultaneous permeation into the cells, the other involved only radial diffusion in homogeneous cylinders of tissue having no internal barriers to diffusion; the former was found to give a better representation of the efflux kinetics.4. If it was assumed that the rate of diffusion of DMSO in the extracellular space of taenia coli was the same as that in the bathing medium, the values of the extracellular space and the permeability of smooth muscle to DMSO, obtained from the analysis of the efflux kinetics, were 454 +/- 19 ml./kg and 2.36 +/- 0.05 x 10(-6) cm sec(-1) at 37 degrees C.5. The activation energy for the transfer of DMSO across the surface of the cell was estimated to be 6.0 kcal/mole at 37 degrees C, 6.6 kcal/mole at 25 degrees C and 11.6 kcal/mole at 0 degrees C, indicating either that the equivalent pore radius of the cells decreased with temperature or that the cell permeability represented the sum of two fluxes, one through the aqueous pores of the cell and the other through the lipid phase of the cell membrane, each with a different energy of activation.6. A net flux of water across the surface of the cells, superimposed on the efflux of DMSO, markedly affected the rate of diffusion of the non-electrolyte out of the whole tissue; however, it was considered that an analysis of the efflux kinetics was not possible under these conditions.7. These results provide a basis for methods which will be used to investigate the possibility of preserving tissue in unfrozen aqueous media at sub-zero temperatures.

Animals↗
PubMed1999

Regulation of fibrillin carboxy-terminal furin processing by N-glycosylation, and association of amino- and carboxy-terminal sequences.

The molecular mechanisms of fibrillin assembly into microfibrils are poorly understood. In this study, we investigated human fibrillin-1 carboxy-terminal processing and assembly using a recombinant approach. Processing of carboxy-terminal fibrillin-1 was strongly influenced by N-glycosylation at the site immediately downstream of the furin site, and by association with calreticulin. The carboxy terminus of fibrillin-2 underwent less efficient processing than carboxy-terminal fibrillin-1 under identical conditions. Size fractionation of the amino-terminal region of fibrillin-1, and of unprocessed and furin-processed carboxy-terminal region of fibrillin-1, revealed that the amino terminus formed abundant disulphide-bonded aggregates. Some association of unprocessed carboxy-terminal fibrillin-1 was also apparent, but processed carboxy-terminal sequences remained monomeric unless amino-terminal sequences encoded by exons 12-15 were present. These data indicate the presence of fibrillin-1 molecular recognition sequences within the amino terminus and the extreme carboxy-terminal sequence downstream of the furin site, and a specific amino- and carboxy-terminal association which could drive overlapping linear accretion of furin-processed fibrillin molecules in the extracellular space. Differences in processing of the two fibrillin isoforms may reflect differential abilities to assemble in the extracellular space.

Endoplasmic Reticulum↗
PubMed1993

Fluid replacement during exercise.

Current evidence indicates that adequate fluid ingestion during exercise enhances athletic performance, prevents a fall in plasma volume, stroke volume, cardiac output and skin blood flow, maintains serum sodium concentrations and serum osmolality, lowers rectal temperature and the perception of effort, and prevents a progressive rise in heart rate. Rates of sweating and urine flow are not influenced by fluid ingestion. The evidence suggests that the maintenance of serum osmolality and serum sodium concentrations at pre-exercise levels is the important determinant of these beneficial effects of fluid ingestion on cardiovascular function and thermoregulation. The provision of glucose in the ingested solution may be necessary to optimize performance; glucose ingestion that enhances fluid and sodium absorption in the small bowel may also present a progressive rise in oxygen consumption during exercise. Sweetened carbohydrate-containing drinks may also increase fluid intake during exercise, thereby minimizing voluntary dehydration. Hence, the optimum solution for ingestion during exercise should provide carbohydrate, probably at rates of about 1 g/min and electrolytes in concentrations that, when drunk at the optimum rate, maintain serum osmolality and plasma volume at pre-exercise levels by replacing exactly that water and electrolyte losses from the extracellular space. At present, the composition of the fluid that will optimize electrolyte and fluid replacement of the extracellular space is not established. Neither are the optimum rates of fluid ingestion during exercise known. At low sweat rates (< 1 liter/hr), it is probable that all of the lost fluid can and should be replaced; rates of fluid ingestion needed to offset higher sweat rates may exceed the maximum intestinal absorptive capacity for water. Furthermore, high rates of fluid intake (> 1 liter/hr) are achieved with difficulty during exercise, especially when running, and are likely to lead to feelings of abdominal discomfort, possibly due to the accumulation of unabsorbed fluid in the small bowel or colon. Practicing to drink regularly during training might reduce the severity and frequency of these symptoms, possibly by increasing intestinal absorptive capacity. Most athletes are "reluctant" drinkers during exercise and do not ingest fluid at rates equal to their rates of fluid loss; hence, they develop progressive (voluntary) dehydration during prolonged exercise. Surprisingly, the level of voluntary dehydration that develops during exercise is relatively independent of the duration or intensity of the activity. The factors that explain these phenomena remain elusive. Fluid consumption during exercise is enhanced by the ingestion of cold, sweet fluids. Simultaneous food consumption also stimulates fluid ingestion.(ABSTRACT TRUNCATED AT 250 WORDS)

Dehydration↗
PubMed1997

Beta 2-agonist regulation of cell volume in fetal distal lung epithelium by cAMP-independent Ca2+ release from intracellular stores.

The effects of beta 2-adrenoceptor agonist (beta 2 agonist) and cAMP on cytosolic Ca2+ concentration ([Ca2+]c) and cell volume were studied in fetal distal lung epithelial cells. Both terbutaline (a specific beta 2 agonist, 10 microM) and dibutyryl cAMP (DBcAMP, 1 mM) increased [Ca2+]c in the presence of extracellular Ca2+. Even in the absence of extracellular Ca2+, the terbutaline-induced increase in [Ca2+]c was still observed, although the increase was transient. However, DBcAMP caused no significant change in [Ca2+]c. In the presence of 1 mM extracellular Ca2+, terbutaline and DBcAMP induced quinine (a blocker of K+ channel) sensitive cell shrinkage. However, in a Ca2(+)-free solution, terbutaline induced rapid cell shrinkage, followed by benzamil (a specific blocker of Na+ channel, an analogue of amiloride) sensitive transient cell swelling. In a Ca2(+)-free solution, DBcAMP induced benzamil-sensitive transient cell swelling without cell shrinkage. Taken together, our observations indicate that the beta 2 agonist induced an elevation of [Ca2+]c by increasing both a Ca2+ influx from the extracellular space and a Ca2+ release from intracellular Ca2+ stores, whereas DBcAMP only stimulated Ca2+ influx from the extracellular space. Furthermore, it is suggested that terbutaline and DBcAMP activated benzamil-sensitive channels independently of an increase in [Ca2+]c.

Adrenergic beta-Agonists↗
PubMed1991

A non-invasive technique for cell volume determination in perfused rat liver.

1) In isolated perfused rat liver, the intracellular ([14C]urea-accessible minus [3H]inulin accessible) water space was determined from the washout profiles of simultaneously infused [3H]inulin and [14C]urea. The washout profile of infused [14C]urea was indistinguishable from that of infused tritiated water. During normotonic perfusions and without hormones or amino acids in influent, the intracellular water space was 548 +/- 10 microliters/g liver wet weight (n = 44). Use of [3H]raffinose instead of [3H]inulin as marker for the extracellular space yielded almost identical values for the intracellular water space (i.e. 98.9 +/- 0.2% of that found with [3H]inulin/[14C]urea). When volume-regulatory K+ fluxes were completed following hypo- and hypertonic exposure of perfused rat livers and a steady state was reached, the intracellular water space was found to be increased and decreased, respectively. The extent of anisotonic exposure was linearly related to the change of intracellular water space. 2) Anisotonicity-, glutamine- and glycine-induced liver mass changes were almost fully explained by the simultaneously occurring alterations of the intracellular water space, indicating that cell volume changes in perfused rat liver under these conditions are not accompanied by significant changes of the extracellular space. Volume-regulatory K+ (plus accompanying anion) efflux following hypotonic perfusion accounted for about 70-85% of regulatory cell volume decrease, which occurred during the first 10 min of hypotonic exposure. 3) Cell volume of isolated hepatocytes was determined as the "hepatocrit" after gentle centrifugation of the cell suspension.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Increased Activity of a Cationic Peroxidase Associated with an Incompatible Interaction Between Xanthomonas oryzae pv oryzae and Rice (Oryza sativa).

Rice (Oryza sativa L.) cultivar Cas 209 carries the gene Xa-10 for resistance to race 2 of Xanthomonas oryzae pv oryzae, the bacterial blight pathogen. When seedling leaves of Cas 209 plants were infiltrated with bacterial cell suspensions of strain PXO86(Rif) (race 2, incompatible), total peroxidase activity in extracts from extracellular spaces increased almost threefold between 16 and 24 hours after inoculation. The increase in total peroxidase activity in extracellular extracts was correlated with the appearance of a 43-kilodalton peroxidase isoenzyme with an isoelectric point of 8.6. Increases in the activities of two anionic peroxidase isoenzymes also were associated with the incompatible interaction. Later during the interactions, total peroxidase activities increased in both compatible (cv Cas 209 infiltrated with race 1, PXO61(Sm)) and control (Cas 209 infiltrated with water) treatments, but final activity levels were less than that observed in the incompatible combination. Similarly, the cationic peroxidase was detected in all three treatments by 48 hours after infiltration, but at reduced levels in compatible and water-infiltrated control treatments relative to the incompatible combination. Accumulation of this peroxidase in extracellular spaces thus may play a role in the defense response in cultivar Cas 209.

Journal Article↗
PubMed1991

Comparative diffusion study of two nitrosoureas: carmustine and fotemustine in normal rat brain, human and rat brain biopsies.

In order to assess the apparent diffusion coefficient of two nitrosoureas (carmustine and fotemustine) in the brain, a model of planar diffusion was used in the rat brain and in rat and human brain biopsies. Drugs were deposed on the brain surface at a constant concentration for 30 min. At the end of the diffusion time, the concentration gradient was determined with microelectrodes using voltammetry at 5 different depths in the extracellular space of the gray matter (0-304 microns). Voltammetry with microelectrodes measured quantitatively intact drug in the brain extracellular space (CV 4% for the 2 drugs) in the range studied. The same procedure was used for human and rat brain biopsies which were held in a small cup. The apparent diffusion coefficients in living animals were 0.49 x 10(-6) cm2.s-1 for carmustine and 0.23 x 10(-6) cm2.s-1 for fotemustine; in human biopsies, they were 0.84 x 10(-6) cm2.s-1 for carmustine and 0.37 x 10(-6) cm2.s-1 for fotemustine. Significant differences in the apparent diffusion coefficients of the drugs were accounted for by the fact that the intracellular penetration of fotemustine was better than that of carmustine.

Adult↗
PubMed1993

Structural and vascular permeability abnormalities associated with lacunes of the human brain.

Histopathological and immune-histochemical studies were carried out in four cases with multiple lacunes of the central grey matter and in control cases without such lesions. Routine light microscopic techniques were applied on paraffin-embedded material to identify lesions that may represent developing lacunes. In addition, polyclonal antisera to human albumin, IgG, fibrinogen and fibronectin were chosen as markers for extravasated plasma proteins. The brain tissue between lacunes contained several forms of focal injuries which may represent precursors of lacunes. Such lesions included foci of status spongiosus and status cribrosus, regions with dilated extracellular spaces and astrocytic gliosis, and multi-locular cysts. These "lacune-associated lesions" often included albumin immune-reactivity in extracellular spaces, nerve cell bodies and astrocytes. Less frequently signs of extravasated IgG, fibrinogen and fibronectin were identified. Thus, lacunes of the human brain frequently showed signs of antigenic sites to albumin. The extracellular deposits probably represent extravasated material from the blood. Vasogenic and cytotoxic oedema combined with other factors probably play important roles during the formation of some of the lacunes.

Aged↗
PubMed1983

Multiple sclerosis: plaques caused by 2-step demyelination?

Selected studies concerning events at the contour of a progressive plaque are reviewed and an explanation of the subtle changes in periplaque white matter which various investigators have observed on autopsy or biopsy is presented. Recurrent exposure to toxic small molecular weight substances carried by arterial blood and capable of diffusing through the walls of blood vessels cause modification of protein or glycoprotein in the myelin sheath. These then act as allergens (modified native tissue considered as 'nonself' tissue by the immune system) which induce antibody formation (termed allo-auto-allergy). Phagocytosis of altered myelin, debris removal and cellular action to maintain homeostasis in the fluid surrounding neurons characterize the premorbid phase of multiple sclerosis. We suggest that the accumulation in the perivascular space of macrophages with large lysosomes digesting myelin debris (visible in electron micrographs) causes bottlenecks in the lymphatic channels serving the extracellular space near nodes of Ranvier. This changes the chemical microclimate and leads to the second step of demyelination and degeneration of the oligodendrocytes, i.e. plaque formation. Reference is made to outstanding problems. Research into the diffusion of small molecular weight substances into the extracellular spaces of white matter would aid in evaluating the hypothesis.

Astrocytes↗
PubMed1997

Maturation of fetal human neural xenografts in the adult rat brain.

Transplantation of human fetal neural cells has been used for several years as a treatment for Parkinson's disease. These therapeutic trials were based on a large number of rat allografts studies, and the species to species extrapolation appeared valid in many respects. One major difference between neurons of various species, however, is their rate of maturation; indeed, human neurons have been proven to grow much more slowly than rat neurons. This has been studied mostly, up to now, at the light microscope level. In an attempt to determine the fine structural correlates of this protracted development and to detail the schedule of morphogenesis and synaptogenesis, human fetal brain stem tissue (at 8 weeks of gestation) was transplanted into a previously lesioned brain area of immunosuppressed adult rats. Transplants, which were allowed to develop for 15 days to 3 months, were analyzed using the electron microscope. At 15 days, small cells containing a large nucleus were surrounded by wide extracellular spaces. At 1 month, grafted neurons displayed a thin rim of cytoplasm and few thin processes. At 2 months, extracellular spaces tended to diminish. Thin processes formed bundles and large processes extended from enlarged neurons. Major changes were observed at 3 months survival as the neuropile filled up with cells and processes and synaptogenesis began. Comparison with a similar ultrastructural study of thalamic rat allografts shows that human cells develop following a pattern similar to that in rat cells but that the duration of each maturation step is largely extended.

Animals↗
PubMed1991

The UL20 gene of herpes simplex virus 1 encodes a function necessary for viral egress.

A recombinant virus from which the start codon and 53% of the UL20 open reading frame had been deleted was constructed and characterized. We report the following: (i) The UL20- mutant formed small plaques in 143 tk- cells but failed to form plaques in Vero cells. Virus yields were approximately 10- to 100-fold lower than those of wild-type virus in all cell lines tested. (ii) Electron microscopic examination of Vero cells infected with the UL20- mutant revealed that enveloped and unenveloped capsids accumulated in the cytoplasm, possibly in the space between the inner and outer lamellae of the nuclear membrane, and that virtually no virus was present in the extracellular space. (iii) Glycoproteins B, C, D, E, H, and I recovered from lysates of cells infected with the UL20- mutant could not be differentiated from those present in lysates of cells infected with the wild-type parent virus with respect to the electrophoretic mobility of mature and precursor forms. (iv) Repair of the deleted sequences restored the wild-type phenotype. (v) The gene product of the UL20 gene was shown to be associated with cellular membranes and to possess characteristics of integral membrane proteins. We conclude that the UL20 gene encodes an integral membrane protein with a hitherto unrecognized function in that it enables the transit of virions to the extracellular space. The function of the UL20 gene product is complemented by some cell lines but not by Vero cells. The vesicles which serve to transport virions may have an origin different from those associated with transport of normal cellular proteins.

Amino Acid Sequence↗
PubMed1997

Intracellular, interstitial and plasma spaces in the rat myocardium in vivo.

The aim of this study was to determine tissue water spaces in rat heart in vivo using [14C]-inulin or D-[14C]-mannitol as extracellular markers, and 2,3DPG as whole blood tissue marker. Tracer was injected into the jugular vein of anaesthetised male Sprague-Dawley rats (60 mg/kg) and allowed to equilibrate for 30 min. A blood sample was then taken and the heart was freeze-clamped at liquid N2 temperatures within 5 s of opening the chest cavity. Extracellular space was calculated by dividing the total tissue counts (d/min/g) by plasma counts (d/min/g). The extracellular inulin and mannitol spaces were 0.212+/-0.010 and 0.236+/-0.012 ml/g wet weight tissue, respectively (n=5). Expressed as a percentage of total tissue water (0.79+/-0.012 ml/g wet weight tissue, n=9), the intracellular space was found to be 73.1 (inulin) and 70.1% (mannitol). The interstitial space was calculated by subtracting the counts in tissue due to whole blood from total tissue counts and dividing by plasma counts. The interstitial space was 19.4 and 21. 9%; and the plasma space was 7.5 and 8.0% for the inulin and mannitol methods, respectively. We conclude that (i) there was no significant differences in the inulin or mannitol spaces in the in vivo heart (P<0.05), demonstrating that either marker provides a reliable and quantitative estimate of extracellular space, and (ii) 2,3-DPG can be used as a reliable indicator of tissue whole blood which can then be used in combination with the tracer method to calculate the interstitial and plasma spaces.

2,3-Diphosphoglycerate↗
PubMed1994

Direct measurement of glutamate release in the brain using a dual enzyme-based electrochemical sensor.

The in vivo measurement of the rapid changes in the extracellular concentrations of L-glutamic acid in the mammalian brain during normal neuronal activity or following excessive release due to episodes of anoxia or ischemia has not been possible to this date. Current techniques for the measurement of the release of endogenous glutamate into the extracellular space of the central nervous system are relatively slow and do not measure the actual concentration of free glutamate in the extracellular space. An enzyme-based electrode with rapid response times (about 1 s) and high degree of sensitivity (less than 2 microM) and selectivity for L-glutamic acid is described in this paper. This electrode has both L-glutamate and ascorbate oxidase immobilized on its surface. The latter enzyme removes almost completely any interferences produced by the high levels of extracellular ascorbate present in brain tissue. The response of the electrode to glutamate and other potentially interfering substances was fully characterized in vitro and its selectivity, sensitivity and rapidity in responding to a rise in extracellular glutamate concentrations was also demonstrated in vivo. Placement of the electrode in the dentate gyrus of the hippocampus led to the detection of both KCl-induced release of L-glutamic acid and the release induced by stimulation of the axons in the perforant pathway. The development of this selective, sensitive and rapidly responding glutamate sensor should make it now possible to measure the dynamic events associated with glutamate neurotransmission in the central nervous system.

Animals↗
PubMed1975

The organization of the nervous system in the crayfish Procambarus clarkii, with emphasis on the blood-brain interface.

Central neural connectives and peripheral nerves of the crayfish Procambarus clarkii are surrounded by an acellular neural lamella, beneath which lies a layer of specialised glia, the perineurium. Cell process of the connective perineurium interdigitate extensively, and are frequently closely associated with each other by gap junctions. Occasional zonulae occludentes are encountered. Nerve perineurium, however, is much less elaborate, and may be reduced to a single or incomplete cell layer. In both connective and nerve, the perineurium appears involved in the formation of the collagen-like fibrils of the neural lamella. The comparative fine structure of connective and peripheral nerve correlates well with recent experimental studies in crayfish, where it was concluded that the perineurium in connective but not nerve offers some restriction to diffusion of small ions and molecules. Within the connective, deeper glia re either closely associated with axons (Schwann cells) or lie relatively free in the extracellular space. Cytoplasmic process of both cell types possess "tubular lattice" systems, which are especially elaborate in the Schwann cells. The extracellular space contains a flocculent material and bundles of collagen, together with layers of basal lamina-like material. The physiological implications of the observations are discussed.

Animals↗
PubMed1981

Structure of the auditory system of the weta Hemideina crassidens (Blanchard, 1851). (Orthoptera, Ensifera, Gryllacridoidea, Stenopelmatidae). 2. Ultrastructure of the auditory sensilla.

This study of the ultrastructure of the auditory sensilla of the New Zealand weta, Hemideina crassidens, is the first such study on a member of the orthopteran Superfamily Gryllacridoidea. Ultrastructure of the auditory sensilla is similar in all of the tibial mechanosensory organs, here called subgenual organ, intermediate organ and crista acoustica by analogy with comparable structures in Tettigoniidae. Distal to each sensory soma is a dendrite containing multiple ciliary rootlets that fuse into a single ciliary root. This splits into nine root processes that pass around the outside of the proximal basal body and then rejoin at the level of the distal basal body, distal to which the dendrite has a modified ciliary structure with a circlet of nine peripheral paired tubes and rods as it passes through the proximal extracellular space. It is then enclosed by a zone of scolopale cell cytoplasm before expanding into a dilatation within the distal extracellular space. In some sensilla this space is partially occluded by electron dense material which is part of the scolopale cell. Distal to the dilatation the cilium shrinks and ends surrounded by the scolopale cap. Accessory cells consist of glia enwrapping the sensory neuron in the region of its soma, the scolopale cell surrouinding the ciliary portion of the dendrite, and the attachment cell surrounding the scolopale cell and scolopale cap and connected to them by desmosomes. The attachment cells are filled with microtubules in differing densities and orientations. Lamellae are present in the acellular matrix surrounding the attachment cells. Banded fibres, presumably of collagen, are also present in the matrix.

Animals↗
PubMed1993

Forces involved in length changes of cochlear outer hair cells.

Motion or force generation of outer hair cells may contribute to active modulation of cochlear mechanics. In order to determine the force involved in length changes of outer hair cells, a new in vitro method was used. In the first series of experiments, apical and basolateral extracellular spaces of outer hair cells of the guinea-pig cochlea were separated. Changes of the voltage between the two extracellular spaces induced reversible, proportional changes of the cell length of 4.4 nm/mV if the cell had a length of 80 microns. In the second series of experiments, cell elongations in response to negative pressure applied to the basal end of the cells were measured and corrected for frictional effects. From these data, the compliance of the longitudinal axis of the hair cells was calculated. It was 220 +/- 130 m/N (n = 25) and 240 +/- 170 m/N (n = 24) for cells of the third and fourth cochlear turns, respectively, if the water permeability of the cell membrane was neglected. If the water permeability was taken into account, the compliance was probably around 500 m/N [corrected]. Thus, a mechanism that changes the cell length by 1 microm must generate a static force of at least around 2 nN in an outer hair cell of the organ of Corti [corrected]. Electromotility of outer hair cells, induced by changes of the electrical potential difference across the outer hair cell, is a mechanism that generates this force.

Animals↗