Effects of L-NAME on cerebral metabolic, vasopressin, oxytocin, and blood pressure responses in hemorrhaged rats
1 Division of Neurosurgery, The University of Texas Medical Branch at Galveston, Galveston, Texas 77555-0517; and 2 Department of Pharmacology, Milton S. Hershey Medical Center, Hershey, Pennsylvania 17033 N G -nitro- L -arginine methyl ester ( L -NAME; 250 µg/5 µl), an inhibitor of NO synthase, o...
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Published in | American journal of physiology. Regulatory, integrative and comparative physiology Vol. 274; no. 4; pp. 1070 - R1077 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
01.04.1998
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Subjects | |
Online Access | Get full text |
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Summary: | 1 Division of Neurosurgery, The
University of Texas Medical Branch at Galveston, Galveston, Texas
77555-0517; and 2 Department
of Pharmacology, Milton S. Hershey Medical Center, Hershey,
Pennsylvania 17033
N G -nitro- L -arginine methyl
ester ( L -NAME; 250 µg/5 µl), an inhibitor of NO synthase, or the vehicle artificial
cerebrospinal fluid (aCSF; 5 µl) was administered
intracerebroventricularly to conscious rats hemorrhaged (0.7 ml/min) to
a 20% volume depletion. Hypotension was maximal 5 min after hemorrhage
ended, with compensatory recovery to basal levels 20 min later,
regardless of drug treatment. L -NAME, however, elevated
( P < 0.05) blood pressure (vs. aCSF controls) 40-45 min after intracerebroventricular administration. In normovolemic rats, L -NAME
produced a significant pressor response and increased plasma levels of
vasopressin (VP) and oxytocin (OT). After hemorrhage, both hormone
levels increased, but only OT was further enhanced by
L -NAME. Thus centrally produced
NO tonically inhibits OT and VP secretion under basal normovolemic
conditions and selectively inhibits OT release during hypovolemia.
Hemorrhage increased the rates of glucose utilization in the neural
lobe, indicative of enhanced efferent neural functional activity.
L -NAME further enhanced the
metabolic activity in the entire hypothalamoneurohypophysial system of
hemorrhaged animals. Several other brain structures involved in the
regulation of blood pressure and the stress response were also
metabolically affected by the hemorrhage and
L -NAME.
nitric oxide; 2-deoxy- D -[ 14 C]glucose; glucose utilization; hypovolemia; neural lobe |
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ISSN: | 0363-6119 0002-9513 1522-1490 |
DOI: | 10.1152/ajpregu.1998.274.4.r1070 |