These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Assessment of selective inhibition of rat cerebral cortical calcium-independent and calcium-dependent phosphodiesterases in crude extracts using deoxycyclic AMP and potassium ions.
    Author: Davis CW.
    Journal: Biochim Biophys Acta; 1984 Mar 01; 797(3):354-62. PubMed ID: 6320906.
    Abstract:
    The effects of various inhibitors on the activity of calcium-independent and calcium-dependent phosphodiesterases from rat cerebral cortex were examined. While the agents varied greatly in their relative potency, each was found to be approximately equipotent in inhibiting the calcium-dependent hydrolysis of either cyclic AMP or cyclic GMP. In contrast, the inhibitors displayed a marked substrate specificity for the calcium-independent enzyme with ratios of IC50 values for inhibition of cyclic GMP hydrolysis when compared to cyclic AMP hydrolysis in decreasing order being: ZK 62711 (much greater than 100) greater than Ro 20-1724 (much greater than 25) papaverine (13) greater than 7-benzyl IBMX (4) greater than quercetin and kaempferol (2). The differential selectivity of the inhibitors for the two enzymes was most pronounced for ZK 62711 and Ro 20-1724 which were at least 25-100-times more potent in inhibiting the calcium-independent hydrolysis of cyclic AMP when compared to the calcium-dependent hydrolysis of cyclic AMP. In contrast, 7-benzyl IBMX, kaempferol and quercetin were 8-100-times more effective as inhibitors of cyclic GMP hydrolysis by the calcium-dependent phosphodiesterase while 7-benzyl IBMX and trimazosin displayed a similar enzyme selectivity using cyclic AMP as substrate. With the exception of papaverine, all agents were competitive inhibitors of the calcium-dependent phosphodiesterase. The type of inhibition observed with the calcium-independent enzyme was dependent on the substrate employed. The specificity of potassium ions in inhibiting the activity of the calcium-dependent phosphodiesterase and deoxycyclic AMP in inhibiting the calcium-independent enzyme was found to provide a convenient means to assess the effects of agents on these activities in crude extracts of cerebral cortex.
    [Abstract] [Full Text] [Related] [New Search]