sodium nitroprusside + bradykinin + acetylcholine

This is a combination of three pharmacologically active agents—sodium nitroprusside, bradykinin, and acetylcholine—each with distinct mechanisms of action but all capable of inducing vasodilation. Sodium nitroprusside is an endothelium-independent nitric oxide donor that directly relaxes vascular smooth muscle by increasing intracellular cGMP levels. Bradykinin and acetylcholine are both endothelium-dependent vasodilators; they stimulate the release of nitric oxide (NO) from endothelial cells via activation of their respective receptors (bradykinin B2 receptor for bradykinin and muscarinic M3 receptor for acetylcholine), leading to smooth muscle relaxation. This combination may be used experimentally to assess vascular reactivity or endothelial function, as each agent can help distinguish between endothelium-dependent and -independent pathways[1][2][4]. There is no evidence this specific triple combination is marketed as a pharmaceutical product.