Modulation of cardiac cell Ca2+ currents by PAF.

Using the whole-cell voltage clamp technique, PAF was found to stimulate T- and L-type Ca2+ currents in a dose dependent manner in both human and chick ventricular single cells. However, PAF had no effect on either the fast sodium current or the delayed outward K+ current in these heart cells. The effect of PAF on both Ca2+ currents was blocked by the PAF receptor antagonist WEB2170. Treatment of single ventricular cells with Pertussis toxin (PTX) prevented stimulation of T- and L-type calcium currents by PAF. These results suggest that there are functional PAF receptors in both human and chick ventricular cells. The stimulation of both types of Ca2+ currents seems to be mediated via a PTX sensitive G-protein.