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Acta Physiologica 2009; Volume 197, Supplement 672
The 60th National Congress of the Italian Physiological Society
9/23/2009-9/25/2009
Siena, Italy
ROLE OF K+ CHANNELS IN THE EXPRESSION OF DEPENDENCE BY A1 RECEPTOR -STIMULATION IN GUINEA PIG ILEUM (GPI)
Abstract number: P119
PALMERY1 M, MHILLAJ1 E, MARTINOLI1 L, ROMANELLI1 L
1Dept of Physiology and Pharmacology V.Erspamer, Sapienza University of Rome; (Italy)[email protected]
Aim:
In previous works we have seen that the A1 adenosine acute withdrawal response in GPI is controlled by indirectly activated opioid system leading to a cross-dependence. In the present study we aimed to see if 4-AP and TEA , known inhibitors of K+ channels could: a) Increase the GPI precipitated contractions when administrated with a selective adenosine A1-receptor agonist, b) Determine a contraction to the adenosine A1-receptor antagonist, CPT in naive preparations
Methods:
The experimental procedure was that used by Valeri et al., (Neuropharmacology, 1996). After a first CPA/CPT test (CPA; 2.9x10-9 M: CPT; 4x10-7 M), GPI preparations were exposed for 5 min to CPA and then challenged with 4-AP (1-4 mM) or TEA (60-240 mM), and 5 min later, with CPT. In subsequent tests the m- and k-opioid antagonist NL (5.4x 10-7M) and BNI (3.4x10-8 M) were added before CPT. In naive GPI preparations 4-AP and TEA were injected before CPT and then before or after NL and BNI.
Results:
Administrated after or without CPA, 4-AP and TEA increased in a dose-related way the contractile response to CPT. Administration of BNI/NL/CPT after the highest dose of 4-AP elicited a strong contraction to BNI, but not increase the ones to the other antagonists.
Conclusion:
The K+ channels can play an important role in the expression of dependence, probably due to the ability of these K+ channel blockers to unmasking the constitutive activity of adenosine A1, m- and k-opioid receptor antagonists
To cite this abstract, please use the following information:
Acta Physiologica 2009; Volume 197, Supplement 672 :P119