Nitric oxide deficiency promotes vascular side effects of cyclooxygenase inhibitors

Area of Science:

• Cardiovascular Pharmacology
• Inflammation and Immunology

Background:

• Cardiovascular safety concerns surround nonsteroidal anti-inflammatory drugs (NSAIDs), particularly COX-2 selective agents.
• Factors predisposing patients to NSAID-related adverse cardiovascular events remain largely unknown.
• Patients with arthritis often exhibit reduced nitric oxide (NO) bioavailability, a critical factor in vascular health.

Purpose of the Study:

• To investigate the in vivo effects of NSAIDs on vascular tone and platelet activity in the presence and absence of NO.
• To elucidate the role of NO in mitigating the cardiovascular side effects of NSAIDs.

Main Methods:

• In vivo studies in murine models examining vascular tone and platelet activity.
• Inhibition of nitric oxide (NO) generation and cyclooxygenase (COX) pathways.
• In vitro myography of aortic rings to assess vascular responses.

Main Results:

• The COX-2 selective NSAID celecoxib demonstrated acute hypertensive and prothrombotic activities only after NO generation was inhibited.
• The nonselective NSAID indomethacin induced hypertension but exhibited antithrombotic effects when NO was absent.
• In vitro, vasoconstriction induced by NSAIDs required simultaneous inhibition of NO synthase (NOS) and COX-2, and was reversed by exogenous NO.

Conclusions:

• Nitric oxide (NO) plays a crucial role in suppressing the vascular side effects of NSAIDs.
• Impaired NO bioavailability, common in conditions like arthritis, may significantly increase the risk of adverse cardiovascular events associated with NSAID use.
• These findings highlight the importance of considering NO bioavailability when assessing cardiovascular risk in patients taking NSAIDs.