Effect of nitroxyl on human platelets function.

Area of Science:

• Biochemistry
• Physiology
• Pharmacology

Background:

• Nitric oxide (NO) is crucial for regulating human platelet function.
• Emerging evidence highlights the role of nitroxyl (HNO/NO-), an alternative redox form of NO, in various biochemical reactions.
• Understanding the distinct effects of NO and HNO on platelets is essential.

Purpose of the Study:

• To comparatively analyze the effects of nitroxyl (HNO) and nitric oxide (NO) on human platelet functional parameters.
• To investigate the mechanisms underlying these effects, including cGMP accumulation and glycoprotein expression.

Main Methods:

• Utilized sodium trioxodinitrate (Angeli's salt, AS) as an HNO donor and sodium nitroprusside (SNP) as an NO donor.
• Assessed platelet aggregation, ATP release, glycoprotein expression (CD41/CD61, CD42b, CD29/CD18, CD9), and activated glycoprotein IIb/IIIa (PAC-1) binding.
• Measured cyclic guanosine monophosphate (cGMP) accumulation, with and without the guanylyl cyclase inhibitor ODQ and the thiol L-cysteine.

Main Results:

• Both AS and SNP significantly inhibited platelet aggregation and ATP release induced by various agonists.
• AS and SNP reduced the expression of CD62P, CD63, and PAC-1 after ADP stimulation but did not alter major platelet glycoprotein levels.
• Both compounds increased cGMP accumulation in an ODQ-sensitive manner, with differential effects observed in the presence of L-cysteine.

Conclusions:

• Nitroxyl (HNO) is demonstrated as an effective inhibitor of human platelet aggregation.
• HNO and NO exhibit distinct modulatory effects on platelet activation markers and signaling pathways.
• Further research into HNO's role in platelet physiology is warranted.