Upregulation of endothelial and neuronal constitutive nitric oxide
synthase in pregnant rats.
Xu, Ding-Li, Pierre-Yves Martin, Judy St John, Phoebe Tsai, Sandra N
Summer, Mamiko Ohara, Jin K Kim, Robert W Schrier.
Department of Medicine, University of Colorado Health Sciences
Center, Denver, Colorado 80262
APStracts 3:0269R, 1996.
Pregnancy is characterized by hemodynamic and body fluid alterations.
Increased NO production has been suggested to play a role in the
hemodynamic alterations of pregnancy and has also been reported to
increase arginine vasopressin (AVP) release. We therefore
hypothesized that gestation could increase both nitric oxide synthase
(NOS) constitutive isoforms, neuronal NOS and endothelial NOS, and
thereby contribute to the hypoosmolality and peripheral arterial
vasodilation of pregnancy, respectively. The present study therefore
was undertaken to examine the constitutive NOS isoforms in aortas,
mesenteric arteries, and hypothalami of pregnant rats on the day 20
of gestation as compared with age-matched non-pregnant rats. Plasma
AVP was determined by radioimmunoassay and hypothalamic mRNA AVP by
solution hybridization assay. Hypothalamic neuronal NOS was assessed
by Northern blot and Western blot, whereas endothelial NOS was
assessed by Western blot in arteries and hypothalamus. The results
demonstrated that: 1) Plasma AVP and hypothalamic AVP mRNA are
increased in pregnant rats (n=8); 2) nNOS protein and mRNA are
increased in hypothalamus of pregnant rats (n=4), and 3) eNOS
expression, using Western blot analysis, is increased in both
conductance (aorta) as well as resistance (mesenteric) arteries of
pregnant rats (n=4). We conclude that both of the constitutive NOS
isoforms are increased in pregnant rats, suggesting that the
peripheral arterial vasodilation and hypoosmolality of pregnancy
could be mediated by these isoforms.
Received 29 January 1996; accepted in final form 14 June 1996.
APS Manuscript Number R59-6.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 25 July 1996