Molecular mechanisms underlying calcium handling in diastolic heart failure

Objective To elucidate molecular mechanisms underlying calcium handling in patients with diastolic heart failure (DHF) from mRNA level and protein expression. Methods 6 patients with DHF and 6 control subjects were included. The content of calcium was assayed by spectrocomparator. The mRNA amounts of these calcium handling genes including L type calcium channel, sarcoplasmic reticular (SR) Ca 2+ ATPase, ryanodine receptor, calsequestrin and phospholamban were measured by reverse transcription polymerase chain reaction (RT PCR) and normalized to the mRNA levels of actin. The protein levels of SR Ca 2+ ATPase and phospholamban were analyzed by Western blot analysis. Results The content of calcium was significantly increased by 369.78% in patients with DHF. RT PCR analyses showed that the steady state level of mRNA encoding the SR Ca 2+ ATPase and cardiac L type calcium channel were decreased significantly in patients with DHF (0.71±0.19 vs 1.07±0.11, P 0.05, 0.74±0.20 vs 1.06±0.13, P 0.05). In contrast, no alterations of the mRNA levels for SR phospholamban, ryanodine receptor, calsequestrin were observed in patients with DHF compared with those in control subjects. Protein level of SR Ca 2+ ATPase was significantly reduced in patients with DHF (0.76±0.11 vs 1.01±0.03, P 0.05), whereas protein level of phospholamban was unchanged. Conclusion The expressions of cardiac L type calcium channel and SR Ca 2+ ATPase were down regulated in DHF. These changes may be a contributory factor for DHF.