[Trabeculae and the intertrabelcular tissue during the contraction of the frog atrium at decreased temperatures and sodium ion concentrations in solution].

Data characterizing the kinetics of the contraction of trabeculae and the intertrabelcular tissue have been obtained. It has been concluded that trabeculae can act as conductors/transmitters of contraction across the myocardium and play a leading role in this process, while the functional role of the intertrabelcular tissue is secondary and more passive, and consists in the optimization and support of the contractile process.

Ca2+-antagonistic properties of phospholipase A2 inhibitors, mepacrine and chloroquine.

The effects of putative phospholipase A2 inhibitors mepacrine and chloroquine on membrane ionic currents were studied in intact frog atrial trabeculae. Both agents decreased slow calcium channel current Isi and fast sodium channel current If. Isi was affected twice at least in comparison to If.