Singlet Oxygen-Induced Arrhythmias

In a study of aerobically perfused rat hearts, the in situ photoactivation (530-590 nm) of rose bengal (a process that leads to the production of singlet oxygen and superoxide) has been shown to lead to the rapid development of electrocardiographic abnormalities and arrhythmias. With rose bengal concentrations of 1,000, 500, 250, 100, and 50 nmol/l (n =6/group), photoactivation (3,600 lx) led to electrocardiographic changes (inversion of the T wave, Q-T prolongation, or both) after 3.8±0.9, 4.5±0.7, 11.8+2.1, 24.8+3.9, and 65.3+6.0 seconds), respectively; ventricular premature beats occurred in 100% of hearts after 0.5+0.2, 1.1±0.3, 2.2±0.7, 4.4±0.8, and 6.6±+1.2 minutes, respectively. Ventricular tachycardia occurred in 83%, 83%, 83%, 67%, and 50% of hearts after 2.1±0.2, 2.1±0.4, 2.8+0.7, 5.7±2.0, and 11.2+1.9 minutes, respectively, and complete atrioventricular block in 100%, 100%, 100%, 100%, and 67% of hearts after 3.8±0.7, 6.5± 1.0, 5.5+0.9, 13.8± 1.0, and 14.1±0.9 minutes, respectively. With a fixed concentration (250 nmol/l) of rose bengal, similar light-response relations were observed. Photoactivation of rose bengal had no eifect on heart rate but caused a transient (0-4 minutes) vasodilation followed by a progressive vasoconstriction. In further studies in which