Leucokinin activates Ca(2+)-dependent signal pathway in principal cells of Aedes aegypti Malpighian tubules

The role of Ca(2+) in mediating the diuretic effects of leucokinin-VIII was studied in isolated perfused Malpighian tubules of the yellow fever mosquito, Aedes aegypti. Peritubular leucokinin-VIII (1 microM) decreased the transepithelial resistance from 11.2 to 2.6 kOmega. cm, lowered the transepith...

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Bibliographic Details
Published in:American journal of physiology. Renal physiology 2002-09, Vol.283 (3), p.F499-F508
Main Authors: Yu, Ming-Jiun, Beyenbach, Klaus W
Format: Article
Language:English
Subjects:
Aedes - metabolism
Animals
Barium - pharmacology
Calcium - pharmacology
Calcium Channel Blockers - pharmacology
Calcium Channels - physiology
Cell Membrane - physiology
Cockroaches
Diuretics - pharmacology
Electric Impedance
Electrophysiology
Insect Proteins - pharmacology
Kinetics
Malpighian Tubules - drug effects
Malpighian Tubules - metabolism
Neuropeptides - pharmacology
Nifedipine - pharmacology
Potassium Channels - physiology
Signal Transduction
Thapsigargin - pharmacology
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Summary:The role of Ca(2+) in mediating the diuretic effects of leucokinin-VIII was studied in isolated perfused Malpighian tubules of the yellow fever mosquito, Aedes aegypti. Peritubular leucokinin-VIII (1 microM) decreased the transepithelial resistance from 11.2 to 2.6 kOmega. cm, lowered the transepithelial voltage from 42.8 to 2.7 mV, and increased transepithelial Cl(-) diffusion potentials 5.1-fold. In principal cells of the tubules, leucokinin-VIII decreased the fractional resistance of the basolateral membrane from 0.733 to 0.518. These effects were reversed by the peritubular Ca(2+)-channel blocker nifedipine, suggesting a role of peritubular Ca(2+) and basolateral Ca(2+) channels in signal transduction. In Ca(2+)-free Ringer bath, the effects of leucokinin-VIII were partial and transient but were fully restored after the bath Ca(2+) concentration was restored. Increasing intracellular Ca(2+) with thapsigargin duplicated the effects of leucokinin-VIII, provided that peritubular Ca(2+) was present. The kinetics of the effects of leucokinin-VIII is faster than that of thapsigargin, suggesting the activation of inositol-1,4,5-trisphosphate-receptor channels of intracellular stores. Store depletion may then bring about Ca(2+) entry into principal cells via nifedipine-sensitive Ca(2+) channels in the basolateral membrane.
ISSN:1931-857X
DOI:10.1152/ajprenal.00041.2002