Dose-dependent effects of crf-like diuretic peptide on
transcellular and paracellular transport pathways.
Clark, Thomas M., Timothy K. Hayes, and Klaus W. Beyenbach.
Department of Zoology, Washington State University, Pullman WA
99164, Bayer Corporation, 1017 Main Campus Drive, Suite 3800,
Raleigh, NC 27606. Section Physiology, VRT 8014, Cornell University,
Ithaca, NY 14853
APStracts 5:0029F, 1998.
The mechanism of action of synthetic Culex CRF-like diuretic peptide
(CCRF-DP) was investigated in isolated, perfused Malpighian tubules
of the yellow fever mosquito Aedes aegypti. Low concentrations of
CCRF-DP (10-10, 10-9 M) caused depolarizing oscillations of the
lumen-positive transepithelial voltage (Vt) in Malpighian tubules,
while high concentrations (10-8, 10-7 M) first depolarized and then
transiently hyperpolarized transepithelial voltage. CCRF-DP always
lowered transepithelial resistance (Rt) regardless of voltage
depolarization or hyperpolarization. The short circuit current (Isc),
an electrical estimate of active transepithelial transport of Na and
K remained unchanged at low concentrations of CCRF-DP, but Isc more
than doubled at high concentrations. These effects of CCRF-DP suggest
dose-dependent sites of action: low concentrations of CCRF-DP affect
the paracellular pathway and high concentrations affect both
paracellular and transcellular pathways.
Received 2 October 1997; accepted in final form 29 January 1998.
APS Manuscript Number F139-7.
Article publication pending Am. J. Physiol. (Renal Physiology).
ISSN 1080-4757 Copyright 1998 The American Physiological Society.
Published in APStracts on 19 February 1998