Effects of interleukin-2 on ventricular papillary muscle of rat and the possible mechanism / 中国应用生理学杂志

ABSTRACT

<p><b>AIM</b>To investigate the effects of interleukin-2 (IL-2) on the transmembrane potential and contractile force in ventricular papillary muscle of rat and the underlying mechanism.</p><p><b>METHODS</b>The transmembrane potentials and contractile force were recorded by intracellular glass microelectrode and tension transducer in the isolated rat papillary muscles.</p><p><b>RESULTS</b>(1) IL-2 shortened the action potential duration (APD50 and APD80), while had no effects on resting potential, action potential amplitude and depolarization rate. (2) IL-2 depressed the contractile force of the muscle in dose-dependent manner. IL-2 at concentrations of 0.5, 2.5, 10, 50 and 200 u/ml decreased the developed tension to 94.8% (P < 0.05), 85.8%, 76.3%, 69.3% and 52.5% (P < 0.01), respectively. (3) Pretreatment with L-NAME (10(-4) mol/L) attenuated the negative inotropic effect of IL-2, in which effect of IL-2 at concentrations from 0.5 to 10 u/ml was completely abolished, and the effect of IL-2 at high dose (50 and 200 u/ml) was partly attenuated by L-NAME.</p><p><b>CONCLUSION</b>IL-2 had inhibitory effects on action potential duration and contractile force of papillary muscle, and its negative inotropic effect was mediated by nitric oxide.</p>