Autor(es): Petzel, D. H.; Pirotte, P. T.; Van Kerkhove, E.

Resumo: In order to understand the critical role that hydrogen ions play in fluid secretion in Malpighian tubules, intracellular and luminal pH and K+ measurements were performed in isolated Malpighian tubules of the yellow fever mosquito (Aedes aegypti). The intracellular pH was 7.03 plus or minus 0.05 (n=15 Malpighian tubules (MT)) and the luminal pH was 7.19 plus or minus 0.09 (n=99 MT) when bathed in saline at a pH of 7.0. The lumen potential is positive, thus net proton secretion into the lumen is active. The intracellular and the luminal K+ concentrations were 75 plus or minus 9 mM (n=15) and 102 plus or minus 13 mM (n=9 MT) respectively. Cyclic AMP analogues accelerated fluid secretion and at the same time acidified the cell without affecting the luminal pH. Both effects were abolished by an isomer of adenosine-3',5' cyclic monophosphothioate (cAMPS), the Rp-cAMPS, known to inhibit protein kinase A. The results suggest that in the presence of cAMP the properties of the cation/H+ exchanger are affected and that this may be a result of phosphorylation of a Na+/2H+ antiporter located on the apical membrane.

Palavras-Chave: Secretion; AMP; pH effects; Malpighian tubules; Cyclic AMP; Aedes aegypti; Culicidae; Freshwater

Imprenta: Journal of Insect Physiology, v. 45, n. 11, p. 973-982, 1999.

Descritores: Aedes aegypti - Cell ; Aedes aegypti - Proteins

Data de publicação: 1999