Intracellular pH transients in response to PCO2 changes were measured in vitro with the weak acid dimethadione (DMO) in gas-equilibrated red blood cells and a perfused trunk preparation (white muscle) of the rainbow trout. Red cell intracellular pH (pH(i)) was also measured directly on cell lysates. At an extracellular pH (pH(e)) of 7.81±0.04, PCO2=2 Torr, red cell pH(i)(lysate) averaged 7.40±0.02, and [DMO](i)/[DMO](e) averaged 0.37±0.02, corresponding to a mean pH(i)(dmo) of 7.39 ±0.02. Decreasing pH(e) to 7.53±0.04 by increasing PCO2 to 8 Torr caused [DMO](i)/[DMO](e) to increase to 0.50±0.03 and resulted in a decline in pH(i) to a mean of 7.19±0.03 as measured by both techniques. With both methods red cell pH(i) responded rapidly (<5min) to the PCO2 of 2 Torr, [DMO](i)/[DMO](e) averaged 0.38±0.03, yielding an average white muscle pH(i) of 7.35±0.04. Decreasing pH(e) to 7.34±0.02 by elevating PCO2 to 15 Torr caused pH(i) to drop to a mean of 7.11±0.03, as indicated by the significant increase in [DMO](i)/[DMO](e) to 0.58±0.03. The response of [DMO](i)/[DMO](e) was complete within 15 min. In both preparations the pH(i) changes were fully reversible. The DMO distribution method for measuring intracellular pH transients proved to be rapid and reliable in fish tissues.
|Journal||American Journal of Physiology - Regulatory Integrative and Comparative Physiology|
|State||Published - Dec 1 1985|
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