Respiratory metabolism of L‐929 cells at different water contents and volumes

Abstract

Oxygen consumption was measured in mouse L-929 cells whose volumes and water contents were reduced by adding sorbitol to the medium. The volume of water lost due to a given sorbitol supplement exceeded the loss in apparent cell volume. An explanation is given for this discrepancy. The rate of oxygen uptake in the absence of exogenous respiratory substrate was essentially the same in cells whose total volume was reduced by 45%, amounting to a loss of about 70% of the total cell water, compared to controls at 'physiological' volume and water content. Cells under these same conditions responded to added substrates (pyruvate, glucose, and glutamine) and inhibitors (iodoacetate and 2-deoxyglucose) in nearly the same way as control cells. These observations are in accord with and add to previous work showing that very large fluctuations in cell volume and water content have only modest effects on the rates and directions of a variety of metabolic processes. The results are interpreted in terms of current views on the composition and organization of the aqueous compartments of eucaryotic cells.

Metabolic and ionic responses of trout hepatocytes to anisosmotic exposure

“…In contrast to hyposmotic medium, hyperosmolarity left V O2 of trout hepatocytes unaltered, despite the fact that the cells were still in a shrunken state at the time respiratory rate was assessed (Fig.·2). Similar observations have been reported for kidney cortex (Gyory et al, 1981) and L-929 cells (Clegg and Gordon, 1985), in which hyperosmotic conditions were also without effect on VO 2 . It has been hypothesised by Clegg and Gordon (1985) that this reflects the highly structured organisation of cellular metabolism, which may render endogenous respiration of the cells largely independent of metabolite concentration in the aqueous cell compartments.…”

L‐929 cells under hyperosmotic conditions: Volume changes

“…5) argues for a nonmetabolic basis and against a completely internalized vesiculation of plasma membrane. We have previously proposed that both invaginations and evaginations of the cell surface accompany volume reduction and provide for surface area storage (Clegg and Gordon, 1985). The preliminary scanning electron microscope observations (Fig.…”

“…We are very far from meeting that requirement (Keith, 1979;Drost-Hansen, 1986; Franks and Maconditions over periods of one hour or more at 37°C (Clegg and Gordon, 1985). These marked alterations in the aqueous compartments were found to have surprisingly little effect on several sampled metabolic pathways, whose rates and directions were, in general, not greatly altered (Mansell and Clegg, 1983;Clegg, 1984).…”

Methods for determination of growth-rate-dependent changes in hybridoma volume, shape and surface structure during continuous recycle

“…8). Even though this determination did not include the change in microvilli surface area or membrane blebbing observed, the results 55 suggest that membrane area may not be a ratedetermining factor in hybridoma respiratory metabolism (Clegg and Gordon, 1985) or Ig secretion. This is in contrast to the correlation between plasma membrane surface area and transferrin secretion rate in isolated hepatocytes (Pechinot et al, 1986) and recent implications that the degree of hybridoma microvilli density may be related to MoAb secretion (Kitano et al, 1988).…”

“…Variation of cell size as a function of growth rate and its relationship to nutrient uptake (Wheatley and Inglis, 1986), protein synthesis (Tarnowka and Baglioni, 1979) and the initiation of mitosis is a fundamental property of mammalian cells (Yen et al, 1975a(Yen et al, , 1975bShields et al, 1978;Brooks and Shields, 1985). Rapid changes in cell volume correlate with hydration (Beall et al, 1975;Clegg and Gordon, 1985;Clegg, 1986;Wheatley et al, 1987) in specific phases of the cell cycle and may also be the result of changing growth medium osmolality (Fish et al, 1973;Wheatley and Angus, 1973;Clegg, 1986). As cell volume changes, surface membrane area, membrane recycling (Novak et al, 1988) and the distribution of blebs and microvilli may also change.…”