Membrane potentials,electrolyte contents,cell pH,and some enzyme activities of fibroblasts |
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Authors: | Y C Yen-Chow S Y Chow W S S Jee D M Woodbury |
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Institution: | (1) Division of Neuropharmacology and Epileptology School of Medicine, University of Utah, Salt Lake City, Utah;(2) Department of Physiology, School of Medicine, University of Utah, Salt Lake City, Utah;(3) Division of Radiobiology, Department of Pharmacology, School of Medicine, University of Utah, Salt Lake City, Utah |
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Abstract: | Summary The resting membrane potential of the cultured fibroblasts derived from rabbit subcutaneous tissues was −10.2±0.20 mV (n=390). This potential was affected by the potassium concentration in the culture medium, but not by other chemical or hormonal
preparations, such as dibutyryladenosine 3′,5′-cyclic monophosphate (0.5 to 5.0 mmol/l), sodium fluoride (10−5 to 10−4
M), hydrocortisone (10−7 to 10−6
M), parathyroid extract (0.5 to 1.0 U/ml), or thyrotrophin (5 to 10 mU/ml). The Na+, K+, and Cl− concentrations of the cultured fibroblasts were 35.4, 85.7, and 22.6 mmol/l cell water, respectively. The water and protein
contents of these cells were 82.1 and 9.18 g/100-g cells, respectively. The intracellular pH of fibroblasts as determined
by 14C] dimethyloxazolidine-2, 4-dione, and3H2O ranged between 6.9 and 7.1 when the pH of the culture medium was maintained at 7.4. The activiities of Na+, K+-, HCO3
−-, and Ca++, Mg++-ATPases in these cultured cells were 19.0±2.1, 13.6±2.1, and 6.6±1.2 nmol pi/mg protein per minute, respectively, and the
carbonic anhydrase activity was 0.054 U/mg protein. Calculations based on the values for the membrane potential and the electrolyte
concentrations observed in this study indicate that Na+, K+, Cl−, and H+ are not distributed according to their electrochemical gradients across the cell membrane. Na+, Cl−, and H+ are actively transported out of the cells and K+ into the cells.
This study was supported by Grant AM20935 from the NIAMDD, NIH, Bethesda, Maryland, and National Aeronautics & Space Administration
NASA-Ames Grant NAG 2-108 and U.S. Department of Energy Contract DE-AC02-76-EV-00119. D. M. W. is the recipient of a Research
Career Award (5-K6-NB-13838), NINCDS, NIH. |
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Keywords: | fibroblast membrane potential electrolytes enzyme activities pH water and protein content |
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