Changes in tension Ca movement and metabolism of guinea pig taenia coli in varying concentrations of external Na and K.

In a previous report (1) it was shown that in guinea pig taenia coli hypertonically added 40 mm K induced a large tension and that both tissue Ca and "Ca uptake of the muscle measured after a 4 minutes wash increased, while in 152 mm K/0 mm Na medium only a small tension remained and '5Ca uptake did not increase while tissue Ca decreased . It has also been shown that the tonic response in hypertonic 40 mm K medium is dependent on aerobic breakdown of carbohydrates and blocked by sodium transport inhibitor (2-4) . The tonic response in 152 mm K/0 mm Na medium was however shown to be unaffected by a sodium transport inhibitor and not solely dependent on aerobic breakdown of carbo hydrates (4). The present investigation is concerned with the changes in tension , uptake of 45Ca measured after a 4 minutes wash and tissue Ca in varying concentrations of Na and K in the external medium, and also the effects of inhibitors of metabolism and sodium transport in guinea pig taenia coli. A part of this work has already been represented (5) .