Background: Alterations in Ca(2+)-handling proteins are thought to underlie the deranged Ca(2+) transients that contribute to deterioration of cardiac function in congestive heart failure (CHF). Clinical trials in CHF patients have shown that treatment with beta-adrenergic receptor antagonists (betaB) improves cardiac performance. The present study determined whether the abundance of Ca(2+)-handling proteins is different in failing hearts from patients treated or untreated with beta B.
Methods and results: Ca(2+) regulatory protein abundance was compared in LV myocardium of 10 nonfailing hearts (NF group) and 44 failing hearts (CHF group) removed at transplantation. Analysis was performed in betaB-treated (betaB-CHF) and non-betaB treated (non-betaB-CHF) patients and in 4 subgroups: ischemic cardiomyopathy (ICM, n=10), nonischemic dilated cardiomyopathy (DCM, n=10), ICM with betaB therapy (betaB-ICM, n=12), and DCM with betaB therapy (betaB-DCM, n=12). Sarcoplasmic reticulum Ca(2+) ATPase, phospholamban, and Na(+)-Ca(2+) exchanger protein abundance were determined by use of Western blot analysis. Ca(2+) transients were measured with fluo-3. Sarcoplasmic reticulum Ca(2+) ATPase was significantly less abundant whereas phospholamban and Na(+)-Ca(2+) exchanger were not significantly altered in non-betaB-CHF versus NF. Sarcoplasmic reticulum Ca(2+) ATPase in the betaB-ICM and betaB-DCM was greater than in non-betaB-CHF and were not different than in NF. Ca(2+) transients in non-betaB-CHF myocytes had significantly smaller peaks and were prolonged versus NF myocytes. Ca(2+) transients from betaB-CHF myocytes had shorter durations than in betaB-CHF myocytes.
Conclusions: betaB treatment in CHF patients can normalize the abundance of myocyte Ca(2+) regulatory proteins and improve Ca(2+)-handling.