Fig. 1.
Effects of extracellular ATP on short-circuit current in mpkCCDc14 cells. A: representative trace of a short-circuit current (Isc) response to addition of ATP (10−5 M) to the apical side of mpkCCDc14 cell monolayers; amiloride indicates addition of amiloride (10−5 M) to the apical side. Addition of ATP caused a response consisting of an initial sharp peak, a second lower peak, followed by a sustained fall in Isc. The sustained fall in Isc reached a level that was lower than that of baseline Isc. B: representative trace of a Isc response when ATP (10−5 M) was added after addition of amiloride (10−5 M). Pretreatment of mpkCCDc14 cell monolayers with amiloride did not influence the initial peak in Isc, but it did eliminate the sustained fall in Isc.