Figure 1.
Representative examples of change in spontaneous AP in response to decrease in CaMKII activity or calmodulin.
Figure 2.
Average changes in (A) spontaneous AP firing rate, (B) ATP and (C) cAMP by decreasing CaMKII activity with KN-93 (high-3 µmol/L, low-0.5 µmol/L), AIP (high-10 µmol/L, low-2 µmol/L), or decreasing calmodulin activity by W-7 (high-50 µmol/L, low-20 µmol/L).
*p<0.05 vs. drug control. #p<0.05 vs. drug low concentration.
Figure 3.
Representative examples of change in Ca2+ transient in response to decrease in CaMKII activity or calmodulin.
Table 1.
Average cells AP induced Ca2+ parameters in control (CON) and following introduction of AIP (n = 6; 2 µmol/L), KN-93 (n = 6; 0.5 µmol/L) or KN-92(n = 5; 3 µmol/L), *p<0.05 vs. drug control.
Table 2.
Average cells AP induced Ca2+ parameters in control (CON) and following introduction of W-7 (20 µmol/L; n = 6), *p<0.05 vs. drug control.
Figure 4.
(A) Decreasing CaMKII activity by KN-93 (high-3 µmol/L, low-0.5 µmol/L), AIP (high-10 µmol/L, low-2 µmol/L), or decreasing calmodulin activity by W-7 (high-50 µmol/L, low-20 µmol/L) decreases spontaneous AP firing rate (n = 10 for each drug), cAMP (n = 4 for each drug) and ATP (n = 5 for each drug).
The inactive KN-93 analog, KN-92 (3 µmol/L), has no significant effect on these measurements. A decrease in the spontaneous AP firing rate is associated with a decrease in cAMP that is linked to a decrease in ATP (B). Thus, a decrease in spontaneous beating rate is associated with reductions in both cAMP and ATP (B and C), and the reduction in ATP is linked to the reduction in cAMP. CaMKII or calmodulin inhibitor effects measured experimentally are illustrated by the symbols. The solid line is the best fit curve for the CaMKII data. The dashed line is the best fit curve for a battery of drugs that reduce Ca2+-cAMP/PKA level measured previously [9].
Table 3.
Average cells AP induced Ca2+ parameters in control (CON) and following introduction of H-89 (0.5 µmol/L; n = 6), *p<0.05 vs. drug control.
Figure 5.
(A) CaMKII inhibition by KN-93 or AIP, or calmodulin inhibition by W-7 decreases O2 consumption in SANC suspension (n = 5 for each drug), (B) AIP decreases mitochondrial flavoprotein fluorescence in single SANC (representative example), indicating a net reduction of flavoprotein pool.
Washout of AIP reverses this effect. *p<0.05 vs. drug control.
Figure 6.
Schematic illustration of the different direct and indirect potential mechanisms of how CaMKII can affect mitochondrial ATP production.