Regulation of epithelial shunt conductance by the peptide leucokinin

Thomas L. Pannabecker, Timothy K. Hayest, Klaus W. Beyenbach

Research output: Contribution to journalArticle

108 Scopus citations

Abstract

Isolated Malpighian tubules of the yellow fever mosquito Aedes aegypti spontaneously secrete NaCl, KCl and water across an epithelium of modest transepithelial resistance (40-80 Ωcm2) and high transepithelial voltage (30-70 mV, lumen positive). Transepithelial electrochemical potentials indicate that Na and K are secreted by active and Cl by passive transport mechanisms. The addition of synthetic leucokinin-VIII (LK-VIII, insect myotropic peptide) to the peritubular bath significantly increases the rates of transepithelial NaCl, KCl and water secretion. In parallel, LK-VIII depolarizes the transepithelial voltage from 59.3 to 5.7 mV, decreases the transepithelial resistance from 57.7 to 9.9 Ωcm2, and renders the basolateral and apical membrane voltages nearly equipotential (∼ -90 mV). Unilateral step changes of the [Cl] in the peritubular bath or tubule lumen elicit small transepithelial Cl diffusion potentials in the absence of LK-VIII but large transepithelial Cl diffusion potentials, up to 85% of Nernst equilibrium potentials, in the presence of LK-VIII. In Malpighian tubules treated with dinitrophenol for estimates of the shunt resistance Rsh, LK-VIII reduces Rsh from 52.5 to 5.8 ωcm2. Bilateral reductions of the Cl concentration in tubule lumen and peritubular bath fully restore Rsh to 55.8 Ωcm2in the presence of LK-VIII. LK-VIII has no effects when presented from the luminal side. These results suggest that LK-VIII increases the Cl conductance of the epithelial shunt via a receptor located at the basolateral side of the epithelium.

Original languageEnglish (US)
Pages (from-to)63-76
Number of pages14
JournalThe Journal of Membrane Biology
Volume132
Issue number1
DOIs
StatePublished - Feb 1 1993

Keywords

  • Malpighian tubule
  • dinitrophenol
  • epithelial shunt pathway chloride conductance
  • leucokinin-VIII
  • myotropic and diuretic peptides

ASJC Scopus subject areas

  • Biophysics
  • Physiology
  • Cell Biology

Fingerprint Dive into the research topics of 'Regulation of epithelial shunt conductance by the peptide leucokinin'. Together they form a unique fingerprint.

  • Cite this