Glyceryl Trinitrate (GTN)

PRODRUG → needs to be denitrated to produce active NO i.e. reacts with sulfylhydryl groups/other enzyme reactions to liberate NO

NO → diffuses into smooth m. cell → binds to & activates GUANYLYL CYCLASE → GTP \( \xrightarrow{\text{GC }} \) cGMP → ↑cGMP

1. Inhibits Ca²⁺ entry into smooth m. cell
2. Activates K⁺ channels → hyperpolarizes cell (inactive)

Stimulates “cGMP dependent protein kinases” → activates MLC phosphatases → dephosphorylates MLC → Smooth muscle relaxation