Effects of leucokinin-VIII on Aedes malpighian tubule segments lacking stellate cells
Autor(es): Yu, M. J.; Beyenbach, K. W.
Resumo: The diuretic peptide leucokinin is known to increase fluid secretion in Malpighian tubules of the yellow fever mosquito Aedes aegypti by increasing a transepithelial Cl super(-) conductance. The present study sought to examine whether stellate cells provided this transepithelial conductance in Aedes Malpighian tubules as they do in Drosophila Malpighian tubules. Aedes Malpighian tubule segments with and without stellate cells were perfused in vitro for measurements of the transepithelial voltage (V sub(t)), resistance (R sub(t)) and Cl super(-) diffusion potentials (DP sub(Cl)). In 11 tubule segments containing both principal cells and stellate cells, 1 mu mol l super(-1) leucokinin-VIII added to the peritubular bath immediately and significantly decreased V sub(t) from 39.3 plus or minus 14.3 mV to 2.3 plus or minus 0.7 mV, decreased R sub(t) from 12.4 plus or minus 2.6 k Omega cm to 2.4 plus or minus 0.3 k Omega cm, and increased DP sub(Cl) from 8.2 plus or minus 1.2 mV to 42.1 plus or minus 5.4 mV. These effects of leucokinin-VIII were qualitatively and quantitatively similar in six tubule segments containing no stellate cells; V sub(t) decreased from 37.8 plus or minus 7.0 mV to 3.4 plus or minus 0.6 mV, R sub(t) decreased from 8.8 plus or minus 2.1 k Omega cm to 1.7 plus or minus 0.2 k Omega cm, and DP sub(Cl) increased from 5.8 plus or minus 2.6 mV to 50.0 plus or minus 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 to increase the Cl super(-) conductance of the paracellular pathway through septate (or tight) junctions.
Palavras-Chave: Cells; Secretion; Peptides; Epithelia; Aquatic insects; Malpighian tubules; Cell junctions; Epithelium; Diuresis; Aedes aegypti; Aedes; Culicidae; Drosophila
Imprenta: Journal of Experimental Biology, v. 207, n. 3, p. 519-526, 2004.
Descritores: Aedes aegypti - Cell
Data de publicação: 2004
