Sensitization by chronic diazepam treatment of A(2A) adenosine receptor- mediated relaxation in rat pulmonary artery

Anikó Ujfalusi, Ágnes Cseppento, Erzsébet Nagy, J. Szabó, Péter Kovács, A. József Szentmiklósi

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

The effects of a 10-day i.p. treatment of rats with diazepam on responses to subtype selective adenosine receptor agonists were studied 3 h, 2 and 8 days after termination of diazepam treatment in isolated cardiovascular tissues possessing distinct adenosine receptors. After long- lasting diazepam exposure, the relaxation elicited by the specific A(2A) receptor agonist CGS 21680 was enhanced in rat main pulmonary arteries (a tissue containing A(2A) adenosine receptors). The increased sensitivity of A(2A) receptors observed 3 h and 2 days after withdrawal of diazepam was completely restored by the 8th day of the wash-out period. N6- cyclopentyladenosine (CPA)-induced suppression in mechanical activity of electrically stimulated rat atrial myocardium (a tissue containing A1 adenosine receptors) was not altered following diazepam treatment. In order to reveal the possible role of inhibition of membrane adenosine transport in the effects of diazepam (a moderate inhibitor of membrane adenosine transport), the action of a 10-day treatment with dipyridamole or S-(p- nitrobenzyl)-6-thioinosine (NBTI; prototypic adenosine uptake inhibitors) was also studied. Dipyridamole or NBTI treatment, like diazepam, increased the responsiveness of rat pulmonary artery to CGS 21680, but did not influence the cardiodepressive effect of CPA in electrically driven left atrial myocardium. The CGS 21680-induced relaxations were significantly antagonized by 10 nM ZM 241385 (a selective A(2A) adenosine receptor antagonist) in vessels of diazepam-treated rats. The relaxation responses to verapamil were unaltered in pulmonary arteries obtained from animals chronically treated with diazepam, dipyridamole or NBTI. These results suggest that chronic diazepam treatment is able to enhance the A(2A) adenosine receptor-mediated vascular functions, but does not modify the responses mediated via A1 receptors of rat myocardium, where nucleoside transport inhibitory sites of membrane are of a very low density. It is possible that sensitization of A(2A) adenosine receptor-mediated vasorelaxation is due to a long-lasting inhibition of membrane adenosine transporter during diazepam treatment.

Original languageEnglish
Pages (from-to)19-25
Number of pages7
JournalLife Sciences
Volume64
Issue number2
Publication statusPublished - Dec 4 1998

Fingerprint

Adenosine A2A Receptors
Diazepam
Pulmonary Artery
Rats
Dipyridamole
Adenosine
Membranes
Myocardium
Tissue
Purinergic P1 Receptor Agonists
Purinergic P1 Receptor Antagonists
Adenosine A1 Receptors
Purinergic P1 Receptors
Membrane Transport Proteins
Verapamil
Nucleosides
Vasodilation
Blood Vessels
Animals

Keywords

  • Adenosine receptor
  • Diazepam
  • Dipyridamole
  • Myocardium
  • NBTI
  • Pulmonary artery

ASJC Scopus subject areas

  • Pharmacology

Cite this

Ujfalusi, A., Cseppento, Á., Nagy, E., Szabó, J., Kovács, P., & Szentmiklósi, A. J. (1998). Sensitization by chronic diazepam treatment of A(2A) adenosine receptor- mediated relaxation in rat pulmonary artery. Life Sciences, 64(2), 19-25.

Sensitization by chronic diazepam treatment of A(2A) adenosine receptor- mediated relaxation in rat pulmonary artery. / Ujfalusi, Anikó; Cseppento, Ágnes; Nagy, Erzsébet; Szabó, J.; Kovács, Péter; Szentmiklósi, A. József.

In: Life Sciences, Vol. 64, No. 2, 04.12.1998, p. 19-25.

Research output: Contribution to journalArticle

Ujfalusi, A, Cseppento, Á, Nagy, E, Szabó, J, Kovács, P & Szentmiklósi, AJ 1998, 'Sensitization by chronic diazepam treatment of A(2A) adenosine receptor- mediated relaxation in rat pulmonary artery', Life Sciences, vol. 64, no. 2, pp. 19-25.
Ujfalusi, Anikó ; Cseppento, Ágnes ; Nagy, Erzsébet ; Szabó, J. ; Kovács, Péter ; Szentmiklósi, A. József. / Sensitization by chronic diazepam treatment of A(2A) adenosine receptor- mediated relaxation in rat pulmonary artery. In: Life Sciences. 1998 ; Vol. 64, No. 2. pp. 19-25.
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