Fig. 5. Effects of bathing saline potassium concentration on tetraethylammonium (TEA) influx (left ordinate) and differential signal (right ordinate) in the (A) lower Malpighian tubule (LMT) and (B) Malpighian tubule main segment. LMTs were bathed in saline containing 10 or 100 mmol l^–1 K⁺. Main segments were bathed in salines containing 20 or 2 mmol l^–1 K⁺. All salines contained 100 µmol l^–1 TEA. The height of each bar represents the mean + S.E.M. (N=4 main segments; N=7 LMTs). Asterisks denote significant differences (P<0.05) from the value of the bar to the immediate left.