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Calcium regulates Na + :K + :2Cl − cotransporter function in Malpighian tubules of Rhodnius prolixus
Author(s) -
Gioino Paula,
Ianowski Juan P
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.1210.5
Subject(s) - rhodnius prolixus , malpighian tubule system , cotransporter , endocrinology , medicine , chemistry , calcium , diuresis , serotonin , homeostasis , ion transporter , biology , kidney , receptor , biochemistry , sodium , midgut , insect , membrane , ecology , botany , organic chemistry , larva
Rhodnius prolixus is a haematophagous insect, vector of Chagas’ disease. During each blood meal the insect ingests large volumes of blood that may be up to 10 times its unfed weight. The excess of water and ion ingested is expelled thanks to a rapid post‐prandial diuresis triggered by the diuretic hormone serotonin, that stimulate the Malpighian (renal) tubules (MT). Until now, serotonin was believed to stimulate MTs via the second messenger cAMP and Ca 2+ was considered to play no significant role. Here we tested the role of Ca 2+ on serotonin‐stimulated MTs. Our results show that serotonin stimulation triggered Ca 2+ waves in MTs. In addition, incubating tubules in Ca 2+ ‐free saline containing BAPTA‐AM (3 μM) reduced fluid transport by 50%, decreased Na + flux by 70% and decreased pH of the secreted fluid from 7.10±0.05 to 6.20±0.21. Measurements of transepithelial potential suggest a reduced activity of the basolateral Na + :K + :2Cl − cotransporter (NKCC) when chelating Ca 2+ . The results indicate that Ca 2+ is important for normal functioning of the tubules. We hypothesize that Ca 2+ may be involved in NKCC regulation. Disruption of Ca 2+ signalling may alter NKCC activity by changing its phosphorylation state or its insertion to the membrane. Funded by a Natural Sciences and Engineering Research Council of Canada grant to JPI.