Figure 6.

(A) Effect of piceatannol in the intracellular Ca²⁺ transients of electrical paced rat ventricular cells and the decay rate of caffeine-induced Ca²⁺ transients. The area under Ca²⁺ transient (AUC) was integrated and averaged from consecutive five beatings in the steady-state condition of control or after applying piceatannol for 5 min from 10 different cells. The decay rate of Ca²⁺ transient was analysed by simple one-exponential equation (n= 10) as shown in the right bottom of (A). (B) Caffeine 10 mmol·L⁻¹ was applied to elicit intracellular Ca²⁺ release in quiet cells which previously had electric pacing to a steady state in the absence and presence of piceatannol as shown in the left panel of (B). The decay rate of caffeine-released intracellular Ca²⁺ was also analysed by simple one-exponential equation. NiCl₂ (3 mmol·L⁻¹) was used to block Na⁺-Ca²⁺ exchange which markedly prolonged the decay time of caffeine-elicited Ca²⁺ transient as shown the measured decay tau in the right panel of (B). Piceatannol 30 µmol·L⁻¹ significantly slowed the decay rate. Data are shown as mean ± SEM (n= 6). *P < 0.05 versus control group by one-way anova with Duncan's new multiple range test.