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Updated: Oct 9, 2026

Platelet-based Detection of Nitric Oxide in Blood by Measuring VASP Phosphorylation
Published on: January 7, 2019
Tetrahydrobiopterin attenuates modulation of platelet 12-lipoxygenase and cyclooxygenase activities by nitric oxide
1Department of Hygienic Chemistry, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan. fujimoto@oysun01.oups.ac.jp
Abstract:
Endothelial cells secrete large amounts of 5,6,7,8-tetrahydrobiopterin (BH(4)) in septic conditions. BH(4) is a cofactor for nitric oxide (NO) synthase and an essential regulator of its activity. We recently showed that NO can be a modulator of both platelet 12-lipoxygenase and cyclooxygenase activities. In the present study, we investigated the effect of BH(4) on the activities of 12-lipoxygenase and cyclooxygenase in rabbit platelets. The influence of BH(4) on NO-induced modulation of these enzyme activities was investigated. Exogenous BH(4) did not affect platelet 12-lipoxygenase and cyclooxygenase activities. The modulatory effects of NO on the two enzymatic pathways were reversed by addition of BH(4) but not by reduced glutathione. These results suggest that exogenous BH(4) is not essential for NO synthase activity of platelets, but that it is an important regulator of the action of NO released from other sources on platelet 12-lipoxygenase and cyclooxygenase activities.
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