Branchial and systemic roles of adenosine receptors in rainbow
trout, an in vivo microscopy study.
Sundin, Lena, and G[diaeresis]oran E. Nilsson.
Department of Zoophysiology, University of G[diaeresis]oteborg, S
-413 90 G[diaeresis]oteborg; Department of Limnology, Uppsala
University, S-752 36 Uppsala, Sweden; Division of General Physiology,
University of Oslo, N-0316 Oslo, Norway
APStracts 3:0106R, 1996.
Lena Sundin and G[diaeresis]oran E. Nilsson. Adenosine A1-receptor
mediated vasoconstriction of trout gill arteries, an in vivo
microscopy study. Am. J. Physiol. 000 (Regulatory Integrative Comp.
Physiol. 00) R000-R000, 1995.- The purinergic branchial vasomotor
control in rainbow trout, (Oncorhynchus mykiss) was studied, using an
epi-illumination microscope equipped with a water immersion
objective. Cardiac output (Q), heart rate, and dorsal (PDA) and
ventral (PVA) aortic pressures were recorded simultaneously. Pre
-branchial injection of adenosine or the A1-receptor agonist N6
-cyclopentyl adenosine (CPA) constricted the distal portion of the
filament vasculature, which coincided with an increase of PVA. The
A2-receptor agonist PD-125944 (DPMA) was without effect. After
adenosine and CPA injection, an overflow of blood to the secondary
system was repeatedly observed unless blood flow came to a complete
stop. The lack of a concomitant reduction of Q, suggested a
redistribution of blood to the secondary system and to more proximal
parts of the filament. The branchial effects of adenosine and CPA
were completely blocked by the unspecific adenosine receptor
antagonist aminophylline and the specific A1-receptor antagonist N6
-cyclopentyl theophylline. The results suggest that A1-receptors alone
mediate the branchial vasoconstriction observed. Thus, the responses
of the branchial vasculature to adenosine includes a vasoconstriction
of the filament vasculature mediated via specific A1-receptors and a
redistribution of blood flow to the secondary system and to proximal
parts of the filament. Additional cardiovascular effects of adenosine
included decreased systemic vascular resistance and heart rate.
Received 7 August 1995; accepted in final form 11 March 1996.
APS Manuscript Number R493-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 27 March 96