Table 1.

Mechanisms of NO Radiosensitization Effects

Treatment	Systemic Effects	Local Effects
NO donors (tumor-type dependent)	Vasodilation and steal effect	Increased oxygenation
	Red blood cell rheology modification	Release of NO by RBCs under hypoxic conditions
		Local Oxygen sparing through NO-mediated mitochondrial effects
TSP-1/CD47 modulation	Increased TSP-1 inhibits NO generation leading to vasoconstriction	Increased tumor blood flow through anti-steal effect
Insulin and electrical stimulus	Increased iNOS activity and NO	Increased tumoral blood flow
Focused low-dose radiation	None	Increased tumor NO through eNOS up-regulation
Hypoxia-activated NO donors	None	Increased local NO concentration, modulation of tumor blood flow