Original Article: PDF OnlyAlloatti G.; Montrucchio, G.; C. Tetta, F. Mariano; Emanuelli, G.; Camussi, G.Journal of Cardiovascular Pharmacology: February 1987 - p 181-186 Free Abstract The role of calcium channels in the mediation of the cardiovascular effects of synthetic (1-O-octadecyl-2-acetyl-sn-glyceryl-3-phosphorylcholine) platelet-activating factor (PAF) was studied in vivo in the rabbit and in vitro in the coronary-perfused isolated heart and papillary muscle of the guinea pig following pretreatment with verapamil, a calcium antagonist. In the rabbit, verapamil (0.3 mg/kg) abrogated the ECG changes, and reduced all the hemodynamic alterations caused by PAF (0.8 mUg/kg). Verapamil (20 nmol) reduced both the electrical and mechanical alterations observed in the isolated heart and papillary muscle after the infusion of PAF (0.2 nmol). These results suggest that the transmembranal calcium channels play a crucial role in the mechanism by which PAF acts on the cardiovascular tissues. © Lippincott-Raven Publishers.