Table 3.

Influence of mitochondria on the velocity of Ca²⁺ waves in a SR vesicle agarose gel.

Excitable medium	Velocity (μm/s)
SR vesicles (Control)	39.2 ± 16.2a (n = 22)
SR vesicles + thapsigargin	19.6 ± 4.4a (n = 8)
SR vesicles + RHM	57.9 ± 12.9b (n = 20)
SR vesicles + RHM + antimycin A	40.9 ± 10.1b (n = 20)

Spontaneous Ca²⁺ waves in a SR vesicle agarose gel were assessed by confocal scanning fluorescence microscopy with Fluo-3. SR vesicles were isolated from the m. longissimi dorsi of German landrace pigs. Rat heart mitochondria (RHM) were isolated with standard procedures. SR vesicles were incubated in a solution with the following composition (mM): KCl 100, MgCl₂ 5, Na₂-ATP 4, Phosphocreatine 10, EGTA 0.04, PIPES 20; Fluo-3 0.01; pH = 7.2. The concentration of agarose gel was 0.66% (86). For Ca²⁺ stimulation we either used a glass tip or a small stripe of paper soaked with Ca²⁺ solution (200 μM). Under the influence of 10 nM thapsigargin, an inhibitor of the SR Ca²⁺-ATPase (SERCA), the velocity of Ca²⁺ waves decreased signifcantly compared to the controls. If mitochondria were added to SR vesicles (together with 10 mM pyruvate plus 2 mM malate as mitochondrial substrates) significantly faster propagating waves were observed. After inhibition of mitochondrial function with 1 μM antimycin A, an inhibitor of complex III of the respiratory chain, this effect was completely abolished. Further details see [86]. Data as mean ± S.D. a, b indicate significant differences between the marked groups (p < 0.01).