Intracellular pH and contraction of isolated XXXX and cat papillary muscle: effect of superfusate buffering.

@entity95 @entity3157 @entity515 @entity520 @entity2701 @entity7482
The influence of external buffering on surface pH (pHs), intracellular pH (pHi) and developed twitch @entity2701 was investigated in @entity95 and cat papillary muscle. pHs and pHi were measured using single and double-barreled microelectrodes respectively. In 20 mM @entity7482 buffered solution, steady state pHi is close to that in control @entity515 /HCO-3 (25 mM @entity3157 , 5% @entity515 ) solution. pHs and developed @entity2701 also do not differ greatly from their control values. Decreasing the @entity7482 concentration to 5 mM, at constant external pH, lowers pHs considerably. The surface @entity520 is associated with a small intracellular acidification; steady state pHi in 5 mM @entity7482 is always more acid than that in control @entity515 /HCO-3. A significant decrease in developed @entity2701 is also seen in 5 mM @entity7482 . Alteration of the superfusion velocity influences pHs only slightly. Stimulation of the muscle at high frequency is shown to increase surface acidification, the extent of which is dependent on the buffer concentration. The conclusion from the present experiments is that in papillary muscle external buffering influences intracellular pH and contraction via its effect on pHs.
