The effects of TMB-8 on the shape changes of vascular endothelial cells resulting from exposure to various inflammatory agents

Pre-treatment of the endothelial cells lining the guinea pig inferior vena cava with 8-(diethylamino) octyl 3,4,5-trimethoxybenzoate (TMB-8) (10 M)in vitro significantly reduced the shape changes resulting from subsequent exposure to platelet activating factor (PAF) (0.1 M), calcium ionophore A23187 (10 M), histamine (300 M), bradykinin (2 M), prostaglandin E₂ (PGE₂) (30 M), or leukotrienes (LT) C₄, D₄ or E₄ (1 M). Since TMB-8 is an intracellular calcium antagonist, this provides evidence to support the suggestion that these inflammatory agents increase the concentration of intracellular calcium which brings about a contraction of the actin-myosin complex resulting in endothelial cell shape changes, and the formation of interendothelial cell gaps.