Abstract
Hemostasis and thrombosis occur by cooperative actions of blood cells and cells from the vessel wall. Platelets and endothelial cells are crucial in both processes and are thought to communicate not only during the formation of a thrombus, but also while the blood is circulating. Recent investigations have suggested that the mutual interactions between these cells reach a high degree of complexity under (patho)physiological conditions. Intercellular communication can be effected in a number of ways: (i) by the constitutive release of messenger molecules from unstimulated platelets and endothelial cells, (ii) by the regulated release of messengers from stimulated cells, and (iii) by the effects of vascular tonus and blood flow on both cells. This review focusses on what is known about the signal transduction mechanisms, by which the compounds released from platelets and endothelial cells influence each others functions and properties. Special attention is also paid to the recently described effects of mechanical stimulation.