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ABSTRACT Summary: The specific activity and kinetic constants of the four forms of cyclic nucleotide phosphodiesterase (PDE) activities of liver obtained at autopsy from patients with and
without Reye's syndrome have been analyzed and compared. Assays were conducted on supernatants of 30,000 × _g_ spun homogenates after dialysis to remove endogenously accumulated
substrate. Km values were derived by the double reciprocal plot method. A higher mean value for the low affinity cAMP activity is found in Reye's subjects (11.36 ± 7.33 × 10-4 M
compared to 3.6 ± 1.73 × 10-4 M for controls). Values for the other forms are similar between groups. Values for controls are: 4.03 ± 1.8 × 10-6 M for the high affinity cAMP PDE activity and
2.57 ± 0.27 × 10-4 M and 8.28 ± 5.74 × 10-8 M for the low plus high affinity cGMP PDE activities. Differences in Vmax values are not statistically significant. At 10 and 500 4mUM cAMP
concentrations, infants exhibit the highest specific activities. When all subjects in each group are included in calculation of the mean specific activity, no difference of significance is
apparent. If all infant values are excluded from both groups, the mean specific activity of the high Km or low affinity cAMP PDE obtained for Reye's subjects is significantly higher
than for control subjects (4.18 ± 2.17 nmol/mg/min compared to 1.52 ± 0.93). Such differences are not observed for the low Km or high affinity cAMP PDE or for the high and low affinity cGMP
PDE enzymes. In supernatant fractions from both groups, the presence of 10-6 M cGMP enhanced the cAMP hydrolyzing capacity. Higher concentrations of cGMP are inhibitory for both forms of
cAMP PDE. Speculation: These observations raise the distinct possibility that children who develop Reye's syndrome may exhibit an altered responsiveness to the polypeptide hormones
which utilize the second messenger system to produce their intracellular effects. SIMILAR CONTENT BEING VIEWED BY OTHERS SPONTANEOUS HYDROLYSIS AND SPURIOUS METABOLIC PROPERTIES OF
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ARTICLE PDF AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * Department of Pediatrics and Department of Medicine, Division of Gastroenterology, University of Tennessee Center for the Health
Sciencies, Ellen S Kang * St. Jude Children's Research Hospital, Memphis, Tennessee, USA Ellen S Kang Authors * Ellen S Kang View author publications You can also search for this author
inPubMed Google Scholar RIGHTS AND PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Kang, E. Cyclic Nucleotide Phosphodiesterase Activities of the Human Liver:
Comparison between Control and Reye's Syndrome Samples. _Pediatr Res_ 12, 761–766 (1978). https://doi.org/10.1203/00006450-197807000-00004 Download citation * Issue Date: 01 July 1978 *
DOI: https://doi.org/10.1203/00006450-197807000-00004 SHARE THIS ARTICLE Anyone you share the following link with will be able to read this content: Get shareable link Sorry, a shareable
link is not currently available for this article. Copy to clipboard Provided by the Springer Nature SharedIt content-sharing initiative KEYWORDS * Adenosine 3′,5′-monophosphate * enzyme
kinetics * guanosine 3′,5′-monophosphate phosphodiesterase * Reye's syndrome