Anne Truong MDMen's Sexual Health Doctor

2 Types Of Nitric Oxide Men Need To Know About #MensHealth

6 Aug 2026 · 1 min

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In this segment of her Men’s Health video, Dr. Anne Truong explains that penile erection relies on two separate nitric oxide (NO) pathways. The first, neuronal nitric oxide (nNOS), is released directly from nerve endings when sexual stimulation occurs, acting as the 'ignition key' that initiates the erection process. The second, endothelial nitric oxide (eNOS), is produced by the endothelial cells lining the penile blood vessels in response to increased blood flow and shear stress, serving as the 'fuel' that sustains and amplifies the erection. She emphasizes that many men and even some clinicians overlook this dual-source mechanism, which is crucial for understanding erectile function and potential therapeutic targets.

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Now, here's what most men, and honestly, a lot of doctors don't fully appreciate. There are actually two separate sources of nitric oxide in the penis, and they have different jobs. The first is called neuronal nitric oxide, or NNOS. This comes from the nerve ending itself. When you receive sexual stimulation, the nerve fires and releases nitric oxide to initiate the Think of it as the ignition key. It starts the engine. The second is called endothelial nitric oxide, or eNOS. It comes from the endothelium, which is the thin inner lining of your blood vessel. As the blood begins to flow and increase shear force against those walls, the endothelial cells produce its own nitric oxide to sustain and amplify the rrrrr. Think of this as the fuel that keeps the engine running.