Leucokinin increases the paracellular Cl– conductance in
Malpighian tubules of Aedes aegypti. (A,B) Leucokinin-VIII increases
the transepithelial secretion of both NaCl and KCl. Numbers in red indicate a
statistical significant difference (P<0.05) from controls; (C)
electrophysiological effects of LK-VIII on the transepithelial voltage
(Vt) and resistance (Rt) and on the basolateral and
apical membrane voltages (Vbl, Va) indicate a
transepithelial short-circuit brought about by the sudden increase in
paracellular Cl– conductance; (D) model of transepithelial
electrolyte secretion in Aedes Malpighian tubules. The
transepithelial transport of Na+ and K+ is active and
mediated by principal cells; the transepithelial transport of
Cl– is passive and mediated by the paracellular pathway and
stellate cells. However, under conditions of diuresis triggered by aedeskinin
or kinin isoforms, the transcellular and paracellular pathways are
electrically so well coupled that the rates of transcellular cation secretion
and paracellular anion secretion are equivalent
(Beyenbach, 2003;
Hayes et al., 1989;
Pannabecker et al., 1993;
Yu and Beyenbach, 2004).