The influence of different clinically used alkaline
buffers on cytoplasmic pH in normal as well as acidotic rat myocardial cells was investigated in this study by means of the fluorescent intracellular probe 2',7'-bis-(carboxyethyl)-5,6-carboxyfluorescein acetoxymethyl
ester (
BCECF-AM). It was shown that both
sodium bicarbonate and
Tris buffer mixture (Tribonat) caused a significant and dose-dependent acidification of the cytoplasm of suspended myocardial cells with normal initial intracellular pH. This decrease was followed by a slow increase during the observation period. The initial cytoplasmic pH value was more easily reached when
Tris buffer mixture was used.
Ringer's acetate also caused a decrease of intracellular pH, but this change persisted and was further amplified during the experiment.
Carbicarb in larger dosages as well as pure
trometamol (Tris) caused a pronounced dose-dependent and lasting intracellular alkalinization. Intracellular
acidosis was achieved by preincubating the cells in
sodium acetate. Addition of
sodium bicarbonate caused an initial and dose-dependent acidification of the cytoplasm followed by a slow increase to values slightly above the induced
acidosis. In contrast,
Tris buffer mixture showed a tendency towards an initial acidification only when larger dosages were used, and correction of the induced
acidosis was possible by use of moderate to large volumes.
Ringer's acetate produced a lasting and dose-dependent decrease of cytoplasmic pH, while
Carbicarb and pure
trometamol caused an immediate, pronounced and persistent alkalinization. Myocardial cells with low initial cytoplasmic pH due to preincubation in an
acid buffer also showed an early decrease of intracellular pH after addition of
sodium bicarbonate and
Tris buffer mixture. In the case of
sodium bicarbonate correction of the
acid-base disturbance was not achieved during the observation period, while this was accomplished by use of larger volumes of
Tris buffer mixture.
Carbicarb in larger volumes caused an increase in intracellular pH. The most significant and persistent increases of cytoplasmic pH was achieved by use of pure
trometamol. In conclusion, the present in vitro study implies that
Tris buffer mixture (Tribonat) is well-suited for correction of intracellular
acidosis since it acts without causing a pronounced initial intracellular
acidosis or a later potentially hazardous huge cytoplasmic alkalinization.