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First published online September 15, 2004
Journal of Experimental Biology 207, 3731-3739 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.01208
The anterior stomach of larval mosquitoes (Aedes aegypti): effects of neuropeptides on transepithelial ion transport and muscular motility
School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, USA
* Author for correspondence (e-mail: onkenh{at}wsu.edu)
Accepted 26 July 2004
The present investigation studied the influence of a number of neuropeptides on semi-open preparations of the isolated and perfused anterior stomach of larval Aedes aegypti. Effects of peptides were observed on the lumen negative transepithelial voltage (Vte) that is present with serotonin in the bath; this voltage most likely reflects active HCO3 secretion involved in alkalization of the larval anterior stomach. The five different A. aegypti allatostatins (allatostatin A 15) all affected Vte in almost identical ways, causing a 1015% reduction of the voltage at 107 mol l1. A. aegypti neuropeptide F and proctolin reduced Vte at submicromolar concentrations. At 106 mol l1, neuropeptide F reduced Vte by 30% and proctolin reduced Vte by 50%. In contrast, A. aegypti allatotropin, A. aegypti head peptides I and III and A. aegypti short neuropeptide F were without effect on Vte. During the investigation it was observed that the peristaltic contractions of the preparations caused a dynamic component of Vte. Peristaltic contractions and the correlated voltage fluctuations depended on the presence of serotonin. Peristaltic activity and Vte deflections were progressively inhibited by A. aegypti head peptides I and III by A. aegypti short neuropeptide F and by A. aegypti neuropeptide F when the peptide concentrations were increased from 108 to 106 mol l1. These observations show that physiological concentrations of some of the tested neuropeptides affect two processes that require coordination: ion transport and motility of the larval anterior stomach.
Key words: Aedes aegypti, allatostatin, allatotropin, anterior stomach, head peptide, larva, midgut, mosquito, neuropeptide F, peristalsis, proctolin, transepithelial voltage
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