The effects of leucokinin-VIII were qualitatively and quantitatively similar in six tubule segments containing no stellate cells; V(t) decreased from 37.8+/-7.0 mV to 3.4+/-0.6 mV, R(t) decreased from 8.8+/-2.1 kOmegacm to 1.7+/-0.2 kOmegacm, and DP(Cl) increased from 5.8+/-2.6 mV to 50.0+/-2.1 mV. Thus, stellate cells are not required for signaling or mediating the effects of leucokinin in Malpighian tubules of Aedes aegypti. The results further support previous observations that principal cells signal the effects of leucokinin-VIII to increase the Cl(-) conductance of the paracellular pathway through septate (or tight) junctions.