Figure 3.
Figure 3. The effects of electrical stimulation on the washout of 36Cl from isolated EDL muscles. Muscles were mounted in holders for isometric contractions, preequilibrated for 15 min in KR buffer at 30°C, and preloaded with 36Cl for 90 min in KR buffer containing 0.3–1.0 µCi/ml 36Cl. Then all muscles were moved into empty tubes and carefully blotted to remove the last drips of buffer adhering to the tissue using thin folded strips of dry filter paper. Then, while staying in the empty thermo-stated tubes, contralateral muscles were either stimulated for 60 s at 60 Hz using 0.2-ms, 10-V pulses or left resting for the same interval of time. This would allow the 36Cl residing in the extracellular space to enter the muscle cells. Then resting and stimulated muscles were taken for counting of 36Cl (results shown at 0 time), and all the other muscles were washed for periods of twice for 5 min, four times for 5 min, four times for 10 min, or four times for 15 min in ice-cold Na+-free Tris-sucrose buffer, blotted on dry filter paper, weighed, and taken for counting (results shown at the indicated time for sampling). On the basis of the 36Cl activity of the buffer used for the 90-min loading, the relative uptake of 36Cl was plotted at the onset of washout and at the time points indicated from 10 to 60 min. The content of 36Cl is given in relative values as percentage of the total uptake per gram of wet weight reached during the 90-min loading period and during the following wash (e.g., at 0 time, the 36Cl taken up in 1 g wet wt corresponds to the 36Cl content in 0.24 ml KR buffer or 24%). The dashed regression lines were plotted for the resting and the stimulated muscles, respectively, and values for r2 and the significance of the correlation (P) are given. Each point in this figure represents the mean of observations with SEM on three to six muscles. The intercepts of the dashed line with the ordinate gave values of 5.8% and 11%, corresponding to 7.4 µmol and 14 µmol 36Cl for the resting controls and the stimulated muscles, respectively.

The effects of electrical stimulation on the washout of 36Cl from isolated EDL muscles. Muscles were mounted in holders for isometric contractions, preequilibrated for 15 min in KR buffer at 30°C, and preloaded with 36Cl for 90 min in KR buffer containing 0.3–1.0 µCi/ml 36Cl. Then all muscles were moved into empty tubes and carefully blotted to remove the last drips of buffer adhering to the tissue using thin folded strips of dry filter paper. Then, while staying in the empty thermo-stated tubes, contralateral muscles were either stimulated for 60 s at 60 Hz using 0.2-ms, 10-V pulses or left resting for the same interval of time. This would allow the 36Cl residing in the extracellular space to enter the muscle cells. Then resting and stimulated muscles were taken for counting of 36Cl (results shown at 0 time), and all the other muscles were washed for periods of twice for 5 min, four times for 5 min, four times for 10 min, or four times for 15 min in ice-cold Na+-free Tris-sucrose buffer, blotted on dry filter paper, weighed, and taken for counting (results shown at the indicated time for sampling). On the basis of the 36Cl activity of the buffer used for the 90-min loading, the relative uptake of 36Cl was plotted at the onset of washout and at the time points indicated from 10 to 60 min. The content of 36Cl is given in relative values as percentage of the total uptake per gram of wet weight reached during the 90-min loading period and during the following wash (e.g., at 0 time, the 36Cl taken up in 1 g wet wt corresponds to the 36Cl content in 0.24 ml KR buffer or 24%). The dashed regression lines were plotted for the resting and the stimulated muscles, respectively, and values for r2 and the significance of the correlation (P) are given. Each point in this figure represents the mean of observations with SEM on three to six muscles. The intercepts of the dashed line with the ordinate gave values of 5.8% and 11%, corresponding to 7.4 µmol and 14 µmol 36Cl for the resting controls and the stimulated muscles, respectively.

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