[Effect of interleukin-2 on intracellular calcium transients in rat ventricular myocytes]

In the present study, we investigated the effect of interleukin-2 (IL-2) on the intracellular calcium in enzymatically isolated ventricular myocytes with the use of the spectrofluorometric techniques. It was shown that IL-2 (2.5 200 U/ml) depressed electrically induced Ca(2+) (i) transients of ventricular myocytes in a dose dependent manner. IL-2 (200 U/ml) did not alter the caffeine releasable pool of Ca(2+). Pretreatment with the non selective opioid antagonist naloxone (10(-8)mol/L) or a specific kappa opioid antagonist nor binaltorphimine (nor-BNI, 10(-8) mol/L) abolished the inhibitory effect of IL-2 (200 U/ml) on the Ca(2+) (i) transients of cardiomyocytes, whereas the specific delta opioid antagonist naltrindole (10(-6) mol/L) did not abolish the inhibitory effect. The effect of IL-2 (200 U/ml) was also abolished after pretreatment with pertussis toxin (PTX, 5 mg/L) as well as phospholipase C (PLC) inhibitor U73122 (5 10(-6) mol/L), but not by tyrosine kinase inhibitor genistein (10(-4) mol/L). It is concluded that the depressant effect of IL-2 on the Ca(2+) (i) transients of isolated ventricular myocytes is mainly mediated by cardiac kappa opioid receptor pathway including a PTX sensitive Gi-protein and PLC, but not by tyrosine kinase.