Accumulation of 3-(N-morpholino)propanesulfonate by osmotically stressed Escherichia coli K-12.

We found that exogenous morpholinopropanesulfonate (MOPS) is concentrated approximately fivefold in the free volume of the cytoplasm of Escherichia coli K-12 (strain MG1665) when grown at high osmolarity (1.1 OsM) in two different media containing 40 mM MOPS. MOPS was not accumulated by E. coli grown in low-osmolarity MOPS-buffered medium or in 1.1 OsM MOPS-buffered medium containing the osmoprotectant glycine betaine. Salmonella typhimurium LT2 did not accumulate MOPS under any condition examined. We infer that accumulation of MOPS by E. coli K-12 is not due to passive equilibration but rather to transport, possibly involving an as yet uncharacterized porter not present in S. typhimurium. Glutamate and MOPS were the only anionic osmolytes we observed by 13C nuclear magnetic resonance in E. coli K-12 grown in MOPS-buffered medium. The increase in positive charge accompanying the increase in the steady-state amount of K+ in cells shifted from low to high external osmolarity appeared to be compensated for by changes in the amounts of putrescine, glutamate, and MOPS. MOPS is not an osmoprotectant, because its accumulation did not increase cell growth rate.

Polyol and vacuole formation in cultured canine lens epithelial cells.

Polyol accumulation and myo-inositol depletion were accompanied by extensive vacuole formation in cultured canine lens epithelial cells that were incubated for up to 96 hr in growth medium supplemented with 30 mM D-galactose or 30 mM D-glucose. These changes did not occur in cells incubated in a hypergalactosemic or hyperglycemic medium which also contained an aldose reductase inhibitor (20 microM sorbinil). In addition, these changes were not observed in lens cells incubated in growth medium supplemented with either 30 mM mannitol, which is known to enter cells only slowly, or in 30 mM L-galactose, which is not a substrate for aldose reductase. The vacuoles were visible at the ultrastructural level after 6 hr of incubation in 30 mM D-galactose and increased in both number and size with time. These vacuoles had a unique fine structure. They did not result from swelling of mitochondria or other cell organelles. As demonstrated cytochemically, they did not represent either lysosomes or Golgi saccules. The proliferation pattern of cells incubated with 30 mM D-galactose was clearly different from that of control cells, but approached normal when an aldose reductase inhibitor was added to the incubation medium. Together these findings suggest that vacuole formation and altered cell proliferation were caused by polyol accumulation and/or myo-inositol loss, both of which result from aldose reductase activity.

Non-bicarbonate buffering of ascites tumor cells in the rat as titrated by strong acids.

Buffer equations originally derived for blood were applied to the in vitro system "ascites tumor cells and ascitic fluid'. Non-bicarbonate buffer values beta(mmol x pH(-1) x 1(-1)) were determined experimentally by titration of ascites, cell free ascitic fluid and cell homogenates with NaOH in the absence of CO2. beta in ascitic fluid, in native ascites and in cell homogenate were beta (F) = 5.9, beta (A) = 16.4 and beta (H) = 24.9, respectively. Intracellular beta value beta (C) calculated from buffer equations depended on the ratio delta pHi/delta pHe. With delta pHi/delta pHe = 1, beta (C) was 38.8. The difference between beta (C) and beta (H) could be partly accounted for by differences in the cellular protein content. With delta pHi/delta pHe = 0.62 as in the presence of CO2, beta (C) becomes 62.6. In the presence of CO2 (see Albers et al., 1981), the extracellular buffering was higher and the intracellular buffering lower than the values titrated in the absence of CO2. It is concluded that in the presence of CO2 and/or HCO3- the apparent intracellular buffering of intact tumor cells results from non-bicarbonate buffering by cell proteins as well as from active or passive ionic exchanges with the extracellular fluid.

Acid-base disorders: application of total body carbon dioxide titration in anesthesia.

Every anesthesiologist is aware of the importance of acid-base determinations, but the multiplicity of duties required in clinical anesthesia often leave time for blood-gas measurements at most. The author presents a relatively simple four-step system for more complete interpretation, with biomathematical back-grounding. In summary, he points out that the dominant parameter remains the patient's clinical history in relation to hydrogen ion, Paco2, and bicarbonate.