The Single Kinin Receptor Signals to Separate and Independent Physiological Pathways in Malpighian Tubules of the Yellow Fever Mosquito
SOUTHERN PLAINS AGRICULTURAL RESEARCH CENTER COLLEGE STATION TX
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In the past we have used the kinins of the cockroach Leucophaea the leucokinins to evaluate the mechanism of diuretic action of kinin peptides in Malpighian tubules of the yellow fever mosquito Aedes aegypti. Now using the kinins of Aedes the aedeskinins, we have found that in isolated Aedes Malpighian tubules all three aedeskinins significantly 1 increased the rate of fluid secretion 2 hyperpolarized the basolateral membrane voltage Vbl, and 3 decreased the input resistance Rin of principal cells, consistent with the known increase in the Cl- conductance of the paracellular pathway in Aedes Malpighian tubules. Aedeskinin-III studied in further detail, significantly increased with an EC50 of 1.5 x10-8 M. In parallel, the Na concentration in secreted fluid significantly decreased, and the K concentration significantly increased. The concentration of Cl- remained unchanged. While the three aedeskinins triggered effects on Vbl, Rin and synthetic kinin analogs which contain modifications of the C-terminal amide pentapeptide core sequence critical for biological activity displayed variable effects. For example, kinin analog 1578 significantly stimulated but had no effect on Vbl and Rin, whereas kinin analog 1708 had no effect on but significantly affected Vbl and Rin. These observations suggest separate signaling pathways activated by kinins. One triggers the electrophysiological response, and the other triggers fluid secretion.
- Medicine and Medical Research