Isolation, localization and cardiovascular activity of tachykinins
from the stomach of the bowfin, amia calva.
Waugh, David, Karen E. Groff, Bjorn Platzack, John H. Youson, Kenneth
R. Olson, and J. Michael Conlon.
Regulatory Peptide Center, Department of Biomedical Sciences,
Creighton University Medical School, Omaha NE 68178, U.S.A., Division
of Life Sciences, Scarborough Campus, University of Toronto, M1C 1A4
Canada, Indiana University School of Medicine, South Bend Center for
Medical Education, University of Notre Dame, Indiana IN 46556,
U.S.A.
APStracts 2:0091R, 1995.
The bowfin is an extant representative of an ancient group of ray
-finned fish with evolutionary connections to modern teleosts. A
peptide with substance P-like immunoreactivity was isolated from an
extract of bowfin stomach and its primary structure was established
as Ser-Lys-Ser-His-Gln-Phe-Tyr-Gly-Leu-Met.NH2. This amino acid
sequence resembles mammalian substance P only in the C-terminal
region of the peptide. A second tachykinin with neurokinin A-like
immunoreactivity isolated from the extract comprises 23 amino acid
residues and shows limited structural similarity to mammalian
neuropeptide _. A randomly distributed population of cells in the
gastric glands of the bowfin were immunostained with an antiserum
raised against substance P but no immunopositive structures were
identified in the surface epithelium, lamina propria or the nerve
plexi of the submucosa. Bolus injections of synthetic bowfin
substance P (0.1 - 10 nmol/kg) into the bulbus arteriosus of
unanesthetized bowfin resulted in a significant and dose-dependent
rise in vascular resistance and arterial blood pressure (P < 0.01)
and fall in cardiac output (P < 0.05) without change in heart rate.
After 5 -10 min, arterial pressure and vascular resistance returned
to pre-injection levels but cardiac output significantly (P < 0.05)
increased over baseline values. The response to the peptide was
unaffected by pre-treatment of the animals with phentolamine. The
study has shown that the stomach of the bowfin synthesizes
tachykinins with novel structural features that display
cardiovascular activity in this species.
Received 11 October 1994; accepted in final form 23 March 1995.
APS Manuscript Number R586-4.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 10 April 1995.