Document Detail


The mechanism of action of the antidiuretic peptide Tenmo ADFa in Malpighian tubules of Aedes aegypti.
MedLine Citation:
PMID:  15235016     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The mechanism of action of Tenebrio molitor antidiuretic factor 'a' (Tenmo ADFa) was explored in isolated Malpighian tubules of Aedes aegypti. In the Ramsay assay of fluid secretion, Tenmo ADFa (10(-9) mol l(-1)) significantly inhibited the rate of fluid secretion from 0.94 nl min(-1) to 0.44 nl min(-1) without significant effects on the concentrations of Na+, K+ and Cl- in secreted fluid. In isolated perfused tubules, Tenmo ADFa had no effect on the transepithelial voltage (Vt) and resistance (Rt). In principal cells of the tubule, Tenmo ADFa had no effect on the basolateral membrane voltage (Vbl) and the input resistance of principal cells (Rpc). Tenmo ADFa significantly increased the intracellular concentration of cyclic guanosine monophosphate (cGMP) from 2.9 micromol l(-1) (control) to 7.4 micromol l(-1). A peritubular [cGMP] of 20 micromol l(-1) duplicated the antidiuretic effects of Tenmo ADFa without inducing electrophysiological effects. In contrast, 500 micromol l(-1) cGMP significantly depolarized V(bl), hyperpolarized Vt, and reduced Rt and Rpc, without increasing antidiuretic potency beyond that of 20 micromol l(-1) cGMP. A plot of peritubular cGMP concentration vs Vbl revealed a steep dose-response between 300 micromol l(-1) and 700 micromol l(-1) with an EC50 of 468 micromol l(-1). These observations suggest a receptor- and cGMP-mediated mechanism of action of Tenmo ADFa. Tenmo ADFa and physiological concentrations of cGMP (< 20 micromol l(-1)) reduce the rate of isosmotic fluid secretion by quenching electroneutral transport systems. The inhibition reveals that as much as 50% of the normal secretory solute and water flux can stem from electrically silent mechanisms in this highly electrogenic epithelium.
Authors:
Richard C Massaro; Lenora W Lee; Ankit B Patel; Daniel S Wu; Ming-Jiun Yu; Brett N Scott; David A Schooley; Kathleen M Schegg; Klaus W Beyenbach
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  The Journal of experimental biology     Volume:  207     ISSN:  0022-0949     ISO Abbreviation:  J. Exp. Biol.     Publication Date:  2004 Jul 
Date Detail:
Created Date:  2004-07-05     Completed Date:  2004-10-05     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0243705     Medline TA:  J Exp Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  2877-88     Citation Subset:  IM    
Affiliation:
Department of Biomedical Sciences, VRT 8004, Cornell University, Ithaca, NY 14853, USA.
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MeSH Terms
Descriptor/Qualifier:
Aedes / metabolism*,  physiology
Animals
Body Fluids / secretion*
Cyclic GMP / metabolism*
Diuresis / drug effects*
Dose-Response Relationship, Drug
Electron Probe Microanalysis
Insect Hormones / pharmacology*,  physiology
Malpighian Tubules / physiology*,  secretion
Membrane Potentials / drug effects
Models, Biological
Patch-Clamp Techniques
Peptide Hormones / pharmacology,  physiology
Second Messenger Systems / physiology
Tenebrio / chemistry*
Chemical
Reg. No./Substance:
0/Insect Hormones; 0/Peptide Hormones; 7665-99-8/Cyclic GMP

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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