Nitric Oxide Signaling in Cardiovascular Physiology and Pathology: Mechanisms, Dysregulation, and Therapeutic Frontiers.

Nitric oxide (NO), a fundamental gaseous signaling molecule, is indispensable for cardiovascular homeostasis. This review synthesizes the expansive field of NO biology within the unifying framework of Nitric Oxide Equilibrium (NOE), i.e., the critical balance between its synthesis, bioavailability, and degradation. In a physiological state, NOE maintains vascular health by regulating blood pressure, preventing thrombosis, suppressing inflammation, and optimizing both cardiac and mitochondrial function. Here, we analyze how NOE disruption, primarily through oxidative stress and enzymatic dysfunction, underlies the pathogenesis of major cardiovascular diseases, including atherosclerosis, heart failure, ischemia-reperfusion injury, and cerebrovascular diseases like stroke. A critical evaluation of therapeutic strategies designed to restore NOE is presented, encompassing classic NO donors and phosphodiesterase-5 inhibitors, alongside next-generation soluble guanylate cyclase modulators and precision nanomedicine approaches. By identifying key knowledge gaps and methodological hurdles, this review charts a course for future research focused on biomarker-guided interventions and personalized medicine. Ultimately, we frame the restoration of NOE as a paramount therapeutic goal, crucial to translating decades of molecular research into effective clinical practice.