Regulation of neuronal (uptake-1 mediated) norepinephrine transport
by s-nitrosothiols: mechanism and influence of autocrine and
paracrine sources of nitric oxide.
Kaye, David M., Stephen D. Wiviott, Lester Kobzik, Ralph A. Kelly, and
Thomas W. Smith.
Cardiovascular Division, Brigham and Women_s Hospital and Harvard
Medical School; and Respiratory Physiology Program, Harvard School of
Public Health, Harvard Medical School, Boston, MA
APStracts 3:0358H, 1996.
Although it has been recently shown that nitric oxide and its
congeners (NOx), including nitrosothiols, may modify catecholamine
turnover in the brain, it is not known whether NOx affect NE uptake
by sympathetic neurons. The nitrosothiol NO donor SNAP (100 [mu]M for
1 hr) elicited a concentration-dependent reduction in desipramine
-sensitive [3H]-NE uptake into PC12 cells (66 + 3%; p < 0.01), or
into cultured rat superior cervical ganglia (74 + 5%; p <
0.001), while desipramine-insensitive [3H]-NE uptake was unaffected,
indicating a selective effect on uptake-1 mediated transport. Short
term co-culture of PC12 cells with microvascular endothelial cells
expressing the inducible NO synthase (NOS2) also exhibited a
reduction in [3H]-NE uptake (33+3%, p<0.001) that could be
prevented by the addition of the NOS inhibitor L-NMMA (1mM).
Endogenous production of NOx by nerve growth factor-pretreated PC12
cells also exhibited a L-NMMA inhibitable reduction in [3H]-NE
uptake. While SNAP resulted in a 10-fold elevation of PC12 cGMP
content (p<0.01), its effect on [3H]-NE uptake was not mimicked
by exposure to 8Br-cGMP. However, the inhibitory effect of SNAP on
uptake-1 mediated [3H]-NE transport could be attenuated by 1 mM
cysteine, a sulfhydryl compound that could act as a sink for NOx
-mediated nitrosation reactions, although cysteine did not affect the
increase in intracellular cGMP with SNAP. These data suggest that an
endogenous NOx source(s) modifies the activity of the uptake-1
catecholamine transporter in postganglionic sympathetic neurons,
which we demonstrate express both NOS1 and NOS3, possibly by S
-nitrosothiol-mediated nitrosylation of regulatory sites on the
transporter.
Received 7 March 1996; accepted in final form 15 August 1996.
APS Manuscript Number H222-6.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 29 August 1996