Preliminary isolation of mosquito natriuretic factor

Abstract

A natriuretic factor that triggers diuresis in isolated Malpighian tubules of the mosquito was isolated from the head of the yellow-fever mosquito Aedes aegypti by passing a saline extract of mosquito heads through low-pressure and then high-pressure liquid chromatography (HPLC) columns. Three fractions with biologic activity eluted during a reverse-phase HPLC linear acetonitrile gradient run. Fraction I depolarized the transepithelial voltage (Vt) of isolated perfused Malpighian tubules but did not not stimulate fluid secretion in the Ramsay assay (J. A. Ramsay, J. Exp. Biol. 31: 104-113, 1954). Fraction II depolarized and fraction III hyperpolarized Vt, and both stimulated fluid secretion three- to fourfold. Even though the effects of fractions II and III on Vt differed, both stimulated fluid secretion by increasing the rate of NaCl secretion without affecting K secretion. The selective stimulation of active secretory Na transport by fraction III is mimicked by cyclic AMP (cAMP), suggesting the second messenger role of cAMP in the effects of fraction III. Because fraction III stimulates a NaCl-rich, as opposed to KCl-rich, fluid, the term mosquito natriuretic factor is proposed for this active fraction.

Protein kinase A dependent and independent activation of the V-ATPase in Malpighian tubules ofAedes aegypti.

“…In A. aegypti, several diuretic peptides have been found that are released to the haemolymph by the central nervous system (Jagge and Pietrantonio, 2008;Beyenbach et al, 2010). Shortly after the onset of a blood meal the natriuretic peptide appears in the haemolymph (Petzel et al, 1985;Wheelock et al, 1988), followed by further peptides that have a non-selective diuretic effect (Coast, 2009). The natriuretic peptide, previously referred to as mosquito natriuretic peptide (MNP) (Petzel et al, 1985) and now known to be the calcitonin-like peptide Anoga-DH 31 , increases the secretion of NaCl-rich fluid in isolated tubules of A. aegypti severalfold (Petzel et al, 1985;Coast et al, 2005).…”

“…Shortly after the onset of a blood meal the natriuretic peptide appears in the haemolymph (Petzel et al, 1985;Wheelock et al, 1988), followed by further peptides that have a non-selective diuretic effect (Coast, 2009). The natriuretic peptide, previously referred to as mosquito natriuretic peptide (MNP) (Petzel et al, 1985) and now known to be the calcitonin-like peptide Anoga-DH 31 , increases the secretion of NaCl-rich fluid in isolated tubules of A. aegypti severalfold (Petzel et al, 1985;Coast et al, 2005). MNP acts via the second messenger cyclic AMP, and its diuretic effects can be duplicated by membrane-permeant cAMP analogues (Petzel et al, 1987;Coast et al, 2005;Beyenbach et al, 2009).…”

The plasticity of extracellular fluid homeostasis in insects

“…Because mammalian plasma (∼290 mOsm) is hypo-osmotic to the hemolymph (354 mOsm), the blood meal causes the hypo-osmotic expansion of the ECF . This is largely corrected by increasing the excretion of urine that is hypo-osmotic (309 mOsm) to the hemolymph Coast et al, 2005;Petzel et al, 1985;. Diuretic hormones that are released from the mosquito head during the ingestion of blood trigger this diuresis (Beyenbach, 2003b;Wheelock et al, 1988).…”

“…At least two diuretic hormones correct the ECF expansion in the first two post-prandial hours Beyenbach and Piermarini, 2011). One is the natriuretic hormone, a calcitonin-like peptide (Coast et al, 2005;Petzel et al, 1985Petzel et al, , 1986) that increases the Na + conductance of the basolateral membrane of principal cells, which increases the transepithelial secretion of Na + (Sawyer and Beyenbach, 1985). The stimulation of active transepithelial secretion of Na + hyperpolarizes the transepithelial voltage to more lumen-negative voltages, thus increasing the paracellular secretion of Cl − Beyenbach, 1983, 1984).…”

Beetle diuretic peptides: The response of mealworm (Tenebrio molitor) Malpighian tubules to synthetic peptides, and cross-reactivity studies with a dung beetle (Onthophagus gazella)

“…The different effects of these peptides across and even within orders should be noted. For example, the cockroach CT-like peptide Dippu-DH 31 has a nonselective effect on the Na + and K + ratio in the cockroach (Furuya et al, 2000) while Anoga-DH 31 , recently shown by Coast et al (2005) to be the previously uncharacterised natriuretic peptide of mosquitoes (Petzel et al, 1985), markedly increases [Na…”