Cap2b, a cardioacceleratory peptide, is present in drosophila and
stimulates tubule fluid secretion via cgmp.
Davies, Shireen A., Graham R. Huesmann, Simon H. P. Maddrell, Michael
J. O'donnell, Nicholas J. V. Skaer, Julian A. T. Dow, and Nathan J.
Tublitz.
Division of Molecular and Cellular Biology, Glasgow University,
Glasgow G12 8QQ, U.K., Institute of Neuroscience, Department of
Biology, University of Oregon, Eugene, OR 97403, U.S.A., Department
of Zoology, University of Cambridge, Downing Street, Cambridge CB2
3EJ, U.K., Department of Biology, McMaster University, Hamilton,
Ontario L8S 4K1, Canada
APStracts 2:0181R, 1995.
A cardioacceleratory peptide, CAP 2b , identified originally in the
Lepidopteran Manduca sexta , stimulates fluid secretion by Malpighian
tubules of the Dipteran, Drosophila melanogaster . HPLC analyses of
adult D. ? melanogaster reveal the presence of a CAP 2b -like peptide
which co-elutes with M. sexta CAP 2b and synthetic CAP 2b and which
has CAP 2b -like effects on the M. sexta heart. CAP 2b accelerates
fluid secretion in tubules stimulated by cAMP, but has no effect on
tubules stimulated by cGMP, implying that it acts through the latter
pathway. By contrast, the action of leucokinin is additive to both
cAMP and cGMP, but not to thapsigargin, suggesting that leucokinin
acts by the elevation of intracellular calcium. CAP 2b stimulation
elevates tubule cGMP levels, but not those of cAMP. By contrast,
leucokinin has no effect on levels of either cyclic nucleotide. CAP
2b or cGMP both increase transepithelial potential difference,
suggesting that stimulation of V-ATPase action underlies the
corresponding increases in fluid secretion. Overall, the results show
that a Drosophila CAP 2b -related peptide acts to stimulate fluid
secretion by Malpighian tubules through the cGMP signalling pathway.
Received 1 February 1995; accepted in final form 14 June 1995.
APS Manuscript Number R82-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 11 July 1995.