Protein kinase a activation is required for interleukin-1 induced
nitric oxide production by cardiac myocytes.
Oddis, Carmine V., Richard L. Simmons, Brack G. Hattler, Mitchell S.
Finkel.
Departments of Pathology, Surgery, Medicine and Pharmacology,
University of Pittsburgh, Pittsburgh, PA 15213
APStracts 3:0116C, 1996.
We have previously reported that interleukin-1[beta] (IL-1) alone
induced the transcription of inducible nitric oxide synthase (iNOS)
mRNA and nitric oxide (NO) production by isolated neonatal rat
cardiac myocytes (CM). The present studies were undertaken to explore
the signal transduction pathways involved in IL-1 induced NO
production by CM. The addition of IL-1 to CM resulted in a peak rise
in both cAMP and protein kinase A (PKA) activities by 10 minutes
followed by rapid declines and return to basal levels within 60
minutes. The PKA inhibitor, KT 5720, completely blocked NO2-
production by IL-1 stimulated CM (p<.01;n=12). The protein
kinase C inhibitor, Calphostin C, had no effect on NO2- production by
IL-1 stimulated CM (p=ns;n=12). The addition of PKA + cAMP to
cytosols derived from IL-1 treated CM did not directly enhance iNOS
enzyme activity (p=ns;n=3). CM treated with IL-1 alone stained
positively for iNOS protein by immunohistochemistry. iNOS staining
was absent in CM treated with IL-1 + KT 5720. KT 5720 resulted in an
earlier disappearance of iNOS mRNA from IL-1 treated CM, as detected
by semi-quantitative RT-PCR. We report for the first time that PKA
(but not PKC) activation is required for IL-1 induced NO production
by CM.
Received 5 January 1996; accepted in final form 22 March 1996.
APS Manuscript Number C9-6.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 16 April 96