Functional Characterization of Phosphodiesterases 4 in the Rat Carotid Body: Effect of Oxygen Concentrations

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Abstract

The non-specific cAMP phosphodiesterase (PDE) inhibitor isobutyl-methylxanthine (IBMX) has been used to manipulate cAMP levels in carotid body (CB) preparations but the characterization of different PDE isoforms in CB has never been performed. PDE4 is one of the PDE families that uses cAMP as a specific substrate and changes its activity and affinity for drug inhibitors according to the degree of its phosphorylation. We investigated the effects of hypoxia on cAMP accumulation induced by different PDE4 inhibitors in the CB based on the hypothesis that acute changes in 02 could interfere with their affinity. Concentration-response curves for the effects of the PDE4 selective inhibitors, rolipram and Ro 20-1724 and IBMX on cAMP were obtained in CBs, removed from rats and incubated in normoxia (20%O-2) or hypoxia (5%O-2). No differences were found between cAMP concentrations in normoxic and hypoxic conditions in the absence of PDE inhibitors. In both conditions, the E-max calculated for IBMX was similar to that of the specific PDE4 inhibitors. Hypoxia shifted the concentration response curves to the left with the following rank order of potency IBMX> RO 20-1724=rolipram and increased E-max by about 25%. This pharmacological approach supports the hypothesis that there is PDE4 activity in CBs that is enhanced by acute hypoxia although the low potency of the PDE4 inhibitors to increase cAMP do not support an important role for PDE4 activation in the O-2-sensing machinery at the CB.
Original languageEnglish
Title of host publicationAdvances in Experimental Medicine and Biology
EditorsC Gonzalez, CA Nurse, C Peers
Place of PublicationBerlin
Pages113-119
Number of pages7
Volume648
DOIs
Publication statusPublished - 2009
Event17th Meeting of the International-Society-for-Arterial-Chemoreception (ISAC) Valladolid, SPAIN, JUL 01-05, 2008 -
Duration: 1 Jan 2008 → …

Conference

Conference17th Meeting of the International-Society-for-Arterial-Chemoreception (ISAC) Valladolid, SPAIN, JUL 01-05, 2008
Period1/01/08 → …

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