Dibutyryl cAMP activates bumetanide-sensitive electrolyte transport in Malpighian tubules

J. L. Hegarty, B. Zhang, T. L. Pannabecker, D. H. Petzel, M. D. Baustian, K. W. Beyenbach

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91 Scopus citations


The effects of dibutyryl adenosine 3',5'-cyclic monophosphate (DBcAMP) and bumetanide (both 10-4 M) on transepithelial Na+, K+, Cl-, and fluid secretion and on tubule electrophysiology were studied in isolated Malpighian tubules of the yellow fever mosquito Aedes aegypti. Peritubular DBcAMP significantly increased Na+, Cl-, and fluid secretion but decreased K+ secretion. In DBcAMP-stimulated tubules, bumetanide caused Na+, Cl-, and fluid secretion to return to pre-cAMP control rates and K+ secretion to decrease further. Peritubular bumetanide significantly increased Na+ secretion and decreased K+ secretion so that Cl- and fluid secretion did not change. In bumetanide-treated tubules, the secretagogue effects of DBcAMP are blocked. In isolated Malpighian tubules perfused with symmetrical Ringer solution, DBcAMP significantly hyperpolarized the transepithelial voltage (V(T)) and depolarized the basolateral membrane voltage (V(bl)) with no effect on apical membrane voltage (V(a)). Total transepithelial resistance (R(T)) and the fractional resistance of the basolateral membrane (fR(bl)) significantly decreased. Bumetanide also hyperpolarized V(T) and depolarized V(bl), however without significantly affecting R(T) and fR(bl). Together these results suggest that, in addition to stimulating electroconductive transport, DBcAMP also activates a nonconductive bumetanide-sensitive transport system in Aedes Malpighian tubules.

Original languageEnglish (US)
Pages (from-to)C521-C529
JournalAmerican Journal of Physiology - Cell Physiology
Issue number3 30-3
StatePublished - 1991
Externally publishedYes


  • 4-acetamido-4'-isothiocynanostilbene-2,2'- disulfonic acid
  • Aedes aegypti
  • Dibutyryl adenosine 3',5'-cyclic monophosphate
  • Electron probe analysis
  • Membrane voltage and fractional resistance
  • Ouabain
  • Secretory diuresis
  • Transepithelial sodium, potassium, and chloride secretion
  • Transepithelial voltage and resistance

ASJC Scopus subject areas

  • Physiology
  • Cell Biology


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