Cardiac dialysis offers a new concise approach to assessment of
cardiac sympathetic nerve terminal abnormalities.
Yamazaki, Toji, Tsuyoshi Akiyama, Hirotoshi Kitagawa, Yuji Takauchi,
Toru Kawada, Kenji Sunagawa.
Department of Cardiac Physiology, Department of Cardiovascular
Dynamics, National Cardiovascular Center Research Institute Suita,
Osaka 565 Japan
APStracts 3:0521H, 1996.
We applied a dialysis technique to the heart of anesthetized cats and
examined whether the concentration of dialysate norepinephrine (NE)
reflected NE disposition at the cardiac sympathetic nerve terminals.
Dialysis probes were implanted in the left ventricular wall and
dialysate NE concentrations were measured as an index of myocardial
interstitial NE levels. Stimulation of stellate ganglia significantly
increased dialysate NE responses which were suppressed by local
administration of an NE releasing inhibitor ( -conotoxin GVIA, 10 M).
Increments in basal dialysate NE levels were correlated with
concentrations of a locally administered neuronal uptake blocker
(desipramine, 1, 10, 100 M). Desipramine (100 M) augmented
stimulation induced dialysate NE responses. Local administration of a
neuronal vesicle uptake blocker (reserpine, 1, 10 M) did not alter
dialysate NE levels but increased dialysate dihydroxyphenyglycol
levels. An NE releasing amine (tyramine, 100 g/ml) was locally
administered to examine NE storage capacity at the nerve terminal.
The tyramine induced NE releasing response was completely abolished
by pretreatment with reserpine (1mg/kg ip). Thus, cardiac dialysis
with local administration of pharmacological tool offers a new,
concise approach to assessment of neuronal NE release, uptake,
vesicle uptake and storage capacity by cardiac sympathetic nerve
terminals.
Received 3 July 1996; accepted in final form 10 October 1996.
APS Manuscript Number H595-6.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996