[Molecular mechanism underlying calcium handling in diastolic heart failure].
OBJECTIVE
To elucidate the molecular mechanism underlying calcium handling in diastolic heart failure (DHF) from mRNA level and protein expression, including L-type calcium channel, sarcoplasmic reticulum (SR) Ca(2+)-ATPase, phospholamban, ryanodine receptor, calsequestrin.


METHODS
DHF was produced in rabbits by abdominal aortic coarctation. The mRNA amounts of these calcium-handling genes were measured by RT-PCR, while the protein levels of SR Ca(2+)-ATPase and phospholamban were analyzed by Western blot analysis.


RESULTS
The content of calcium was significantly increased in myocardium of rabbits with DHF than in the myocardium of sham-operated rabbits. The SR Ca(2+)-ATPase activity of DHF rabbits was significantly reduced compared with that in sham-operated rabbits (21.1 micromol.mg(-1).h(-1) +/- 5.7 micromol.mg(-1).h(-1) vs 10.5 micromol.mg(-1).h(-1) +/- 2.8 micromol.mg(-1).h(-1), P < 0.01). RT-PCR analyses showed that the steady-state level of mRNA encoding the L-type calcium channel and SR Ca2+-ATPase was decreased significantly in rabbits with DHF compared with that in the sham-operated rabbits (micromol.mg(-1).h(-1)): 0.75 +/- 0.11 vs 1.20 +/- 0.33; 0.76 +/- 0.12 vs 1.24 +/- 0.38, P < 0.05). The SR Ca(2+)-ATPase mRNA level correlated negatively well with left ventricular relaxation time constant and left ventricular end-diastolic pressure (r = -0.81, -0.64, respectively, P < 0.05 approximately 0.01); the mRNA level of L-type calcium channel correlated negatively with left ventricular end-diastolic pressure (r = -0.74, P < 0.05). The mRNA level of ryanodine receptor correlated negatively with the left ventricular relaxation time constant too (r = -0.71, P < 0.05). Protein level of SR Ca(2+)-ATPase was significantly lower in rabbits with DHF than in the sham-operated rabbits (0.76 +/- 0.6 vs 1.02 +/- 0.09, P < 0.05), whereas the protein level of phospholamban was unchanged.


CONCLUSIONS
The L-type calcium channel and SR Ca(2+)-ATPase were down regulated in DHF. These changes may be a contributory factor for DHF.
Zhong
M
M
Department of Senior Health Care, Qilu Hospital of Shandong University, Jinan 250012, China.
Zhang
Y
Y
Zhang
W
W
D000818:Animals; D001794:Blood Pressure; D002118:Calcium / Q000378:metabolism*; D020746:Calcium Channels, L-Type / Q000235:genetics / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000235:genetics / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism; D004195:Disease Models, Animal; D015870:Gene Expression; D006333:Heart Failure / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases
D020746:Calcium Channels, L-Type; D002147:Calmodulin; D012333:RNA, Messenger; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D000252:Calcium-Transporting ATPases; D002118:Calcium