Camp enhances inducible nitric oxide synthase mrna stability in
cardiac myocytes.
Oddis, Carmine V., Richard L. Simmons, Brack G. Hattler, Mitchell S.
Finkel.
Departments of Pathology, Surgery, Medicine, and Pharmacology,
University of Pittsburgh School of Medicine, Pittsburgh, PA 15213
APStracts 2:0269H, 1995.
The effects of cAMP on cardiac myocyte nitric oxide (NO) production
were studied. Maximal nitrite (NO2-) production by cultured neonatal
rat cardiac myocytes was achieved with 500 U/ml interleukin-1[beta]
(IL-1) for 48 hrs. (4.6+/-0.3 nmole/1.25x105 cells;n=12). Cardiac
myocytes exposed to 500 U/ml IL-1 for 48 hrs. stained positively for
iNOS by immunohistochemistry. Forskolin (FORSK; adenylate cyclase
stimulator) or dibutyryl cAMP (dBcAMP; membrane permeable cAMP
analogue) administration alone had no effect on NO2- production. The
addition of FORSK or dBcAMP to IL-1 significantly increased NO2-
levels vs. IL-1 alone (9.7+/-0.6 and 10.9+/-0.8 vs. 4.6+/-0.3
nmole/1.25 x 105cells/48hrs., respectively;p<.01;n=12).
Semiquantitative RT-PCR revealed increased iNOS mRNA in myocytes
treated with FORSK+IL-1 or dBcAMP+IL-1 vs. those treated with IL-1
alone. The addition of FORSK or dBcAMP to IL-1 increased iNOS mRNA
half-life over IL-1 treatment alone (10.6,11.7 vs. 2.4 hrs.,
respectively). Cardiac myocytes do not express iNOS in response to
cAMP alone. Rather, cAMP enhances iNOS mRNA stability following
cytokine exposure.
Received 27 April 1995; accepted in final form 20 June 1995.
APS Manuscript Number H392-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 11 July 1995.