[The protective action of adenosine in the development of the "calcium paradox" in the isolated heart].

Calcium repletion (2.0 mM) after 10 min of calcium depletion (pCa = 7) resulted in the loss of myoglobin, decreased contents of ATP and adeninucleotides. Adenosine in concentration 50-1000 mcM depressed the release of myoglobin and prevented depletion of ATP and adenine nucleotides during the "calcium paradox". Theophylline, a non-selective A1-receptors blocker did not alter either "calcium paradox" development or protective effect of adenosine. Dipiridamole, an inhibitor of transmembrane transport of adenosine, protected hearts against the "calcium paradox" depending on the concentration. Dipiridamole (50 mcM) abolished protective effect of high concentrations (100-1000 mcM) of adenosine. The results obtained prove that transmembrane transport of adenosine is more important than its interaction with receptors for its protective effect under the "calcium paradox".