STUDY OF BEATING FREQUENCY OF A SINGLE MYOCARDIAL-CELL .3. LASER MICRO-IRRADIATION OF MITOCHONDRIA IN THE PRESENCE OF KCN OR ATP

Mitochondria of a single rat myocardial cell were irradiated in the visible range with a Q-switched laser microbeam over an area of about 5 μm. The beating frequency was increased in one cell out of three after laser micro-irradiation without appreciable temperature change. The presence of KCN or ATP in the culture medium inhibited this effect. Various mechanisms of stimulation such as membrane damage, mitochondrial Ca2+ release or ATP photoproduction are discussed. The results indicate that change in ATP level is the most likely mechanism of stimulation. © 1979.