A STUDY OF PLATELET ACTIVATION DURING HUMAN CARDIOPULMONARY BYPASS AND THE EFFECT OF S-NITROSOGLUTATHIONE

Cardiac surgery is complicated by the occurrence of post-operative ble eding due to platelet dysfunction. This is largely caused by platelet activation and consumption during cardiopulmonary bypass. Patients und ergoing cardiac surgery requiring cardiopulmonary bypass were studied to determine whether early platelet changes due to bypass could be inh ibited using the platelet-selective nitric oxide donor S-nitroso-gluta thione (GSNO). Flow cytometry was used to measure platelet surface exp ression of P-selectin (an alpha-granule protein) and glycoproteins (GP ) IIb/IIIa and Ib (mediators of aggregation and adhesion) before and 5 and 10 min after commencing cardiopulmonary bypass, in 6 controls and 6 patients receiving GSNO 50 mu g/min. Platelet P-selectin expression increased during bypass both in controls and patients receiving GSNO. Glycoproteins IIb/IIIa and Ib fell during bypass in control and GSNO- treated patients. There was no difference between control and GSNO-tre ated groups. Thus no significant platelet inhibition by S-nitrosogluta thione was demonstrated under these conditions.