Original ArticlesDivalent cations and the protein surface co-ordinate the intensity of human platelet adhesion and P-selectin surface expressionWhiss, P. A.; Andersson, R. G. G.Author Information The authors are with the Division of Pharmacology, Department of Medicine and Care, Faculty of Health Sciences, Linköpings Universitet, Linköping, Sweden. (Received 12 November 2001; revised 18 March 2002; accepted 25 March 2002) Sponsorship: This study was supported by grants from the County Council of Östergötland (2000/079), the Swedish Lions Club Research Foundation, the Swedish Society for Medical Research, and the Lars Hierta Memorial Foundation. Address correspondence to Per A. Whiss, Ph.D., Division of Pharmacology, Faculty of Health Sciences, SE-581 85 Linköping, Sweden. Tel: (+46) 13 221478; fax: (+46) 13 149106; e-mail: [email protected] Blood Coagulation & Fibrinolysis: July 2002 - Volume 13 - Issue 5 - p 407-416 Buy Abstract At sites of blood vessel injury, platelets adhere to exposed vessel components, such as collagen, or immobilized fibrinogen derived from plasma or activated platelets. The divalent cations Mg2+ and Ca2+ are essential for platelet adhesion and activation, but Mg2+ can also inhibit platelet activation. The present study evaluates, by an enzymatic method, the effects of various divalent cations on the adhesion of isolated human platelets to collagen, fibrinogen, albumin or plastic in vitro. By enzyme-linked immunosorbent assay, platelet surface expression of P-selectin was measured to estimate the state of activation on adherence. Mg2+ increased platelet adhesion exclusively to collagen and fibrinogen at physiologically relevant concentrations. At higher concentrations, the adhesion declined. Ca2+ induced a weak adhesion only to fibrinogen at physiological doses and a peak of increased adhesion to all protein-coated surfaces at 10 mmol/l. Mn2+ elicited dose-dependent adhesion only to collagen and fibrinogen. Zn2+, Ni2+ and Cu2+ increased the adhesion of platelets independently of the surface. Ca2+ dose-dependently inhibited adhesion elicited by Mg2+ to collagen and fibrinogen. No other combination of divalent cations elicited such an effect. Mg2+-dependent platelet adhesion to collagen and Ca2+-dependent adhesion to fibrinogen increased P-selectin expression. Thus, the present study shows that the outcome of the platelet adhesion depends on the surface and the access of divalent cations, which co-ordinate the intensity of platelet adhesion and P-selectin surface expression. © 2002 Lippincott Williams & Wilkins, Inc.