Figure 6.

Effects of S-nitrosoglutathione (GSNO) after ISO on Ca²⁺ transients and sparks in wild-type (WT) or CaMKIIδ (Ca²⁺/calmodulin kinase II delta)-C273S and -C290A cardiomyocytes. WT, CaMKIIδ-C273S, and -C290A myocytes were stimulated at 0.5 Hz and exposed to 100 nmol/L ISO, then following ISO exposure myocytes were exposed to 150-μM GSNO. Experimental protocol used for Ca²⁺ imaging, the gray bars represent when line-scan images were acquired (A). Mean Ca²⁺ transient amplitude (B) and decay (C) data are shown for cardiomyocytes in response to ISO and washout with GSNO (WT: n=20 cells, N=9 hearts; CaMKIIδ C273S: n=7 cells, N=5 hearts; CaMKIIδ-C290A: n=13 cells, N=5 hearts). Representative line-scans from quiescent WT, CaMKIIδ-C273S and -C290A cardiomyocytes under indicated conditions (D). Mean Ca²⁺ spark frequency data (E) are shown for cardiomyocytes in response to ISO with washout with GSNO (WT: n=18 cells, N=9 hearts; CaMKIIδ C273S: n=8 cells, N=5 hearts; CaMKIIδ-C290A: n=17 cells, N=5 hearts). All data are normalized to baseline control before addition of ISO. ISO indicates isoproterenol.