PubMed · 6727930
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1984-06-14. Serum osmolality.. https://doi.org/10.1056/nejm198406143102417
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As was shown in our previous work, the intracellular pH (pHi) of cultured human fibroblasts depends on cell density. The pHi is low in single cells, higher in cells, forming small groups and maximal in a sparse monolayer. On the other hand, the pHi is low in areas of confluent monolayers. In the present work, we show that the effects of inhibitors of various pH-controlling mechanisms as well as inhibitors of key enzymes in signal transduction pathways depend on the local cell density. We have found that N-ethylmaleimide and 7-chloro-4-nitrobenz-2-oxa-1,3-diazole, known as inhibitors of V-type H+ ATPase, inhibit the elevation of pHi induced by cell-cell contact interactions; meanwhile Cd2+ ions, which inhibit H+ conductive pathway, cause an increase of pHi in a confluent monolayer. Our data revealed also that the Na+/H+ antiporter does not play an essential role in the pHi regulation by intercellular contacts. Inhibitors of phospholipase A2 (4-bromophenacyl-bromide), phospholipase C (neomycin) and protein kinase C (H-7) dramatically change the way the pHi is modulated by local cell density. It is suggested that cell-cell interactions regulate cell activities via modulation of pHi, which is under positive control from phospholipase A2 and under negative control from protein kinase C.
METHOD: Eighteen hospitalized patients with candiduria were treated with oral potassium-sodium-hydrogen citrate to alkalinize the urine. The results obtained were compared with those observed in an untreated retrospective control group. Dosage was adjusted in accordance with the pH of the urine measured immediately before treatment with the aim of achieving a pH of 7 to 7.5. RESULTS: All patients had an indwelling catheter, which is a predisposing factor for candiduria. In 16 out of 18 patients (89%) treatment with potassium-sodium-hydrogen citrate raised pH and resulted in the disappearance of candiduria. Duration of treatment varied between two days and one month (mean: seven days). In four patients the urine became completely sterile; during treatment 12 out of 18 patients developed significant bacteriuria (in eight cases of these the indwelling catheter had been left in place). CONCLUSIONS: Alkalinization of the urine is a simple and effective method of treating candiduria in patients with an indwelling catheter. An additional advantage is the metaphylaxis and prophylaxis of renal stone formation in immobilized patients.
The mechanisms involved in intracellular pH (pHi) recovery from an acid load have been investigated in enterocytes isolated from chicken. Following an intracellular acidification, by abrupt withdrawal of NH4Cl, pHi alkalinized in the nominally absence of Na+ and bicarbonate. This Na(+)- and bicarbonate-independent (NBI) regulatory cell alkalinization became negligible when the pHi has reached a value of approx. 6.85. Addition of Na+ induced a rapid pHi recovery to control values. Rotenone, DCCD, vanadate, NBD-Cl, SCH 28080 and EIPA inhibited the NBI cell alkalinization, whereas bafilomycin A1, ouabain and H2-DIDS were without effect. Na(+)-dependent pHi recovery from an acid load was inhibited by EIPA and unaffected by SCH 28080 or DCCD. The rate of NBI cell alkalinization was a linear function of the electrochemical proton gradient. In high external K+ buffer plus valinomycin the line goes through the origin. Gramicidin accelerated the rate of NBI cell alkalinization, whereas it was slightly reduced by low external potassium. The results demonstrate that in intestinal epithelial cells exist at least two mechanisms for proton secretion: a Na(+)-H+ exchanger and a Na(+)- and bicarbonate-independent proton transport system. This latter mechanism appears to be a proton conductance pathway.