Biochemical changes and their relationship with morphological and functional findings in pig heart subjected to lasting volume overload: a possible role of acylphosphatase in the regulation of sarcoplasmic reticulum calcium pump.
We evaluated the changes in sarcoplasmic reticulum (SR) function and the parallel hemodynamic and morphological modifications in a heart subjected to volume overload. We also determined the levels of acylphosphatase, a cytosolic enzyme, that could play a regulatory effect on SR Ca(2+) pump by hydrolyzing the phosphorylated intermediate of this transport system. For this, swine hearts were subjected to volume overload by aorta-cava shunt for 1, 2, or 3 months. Changes in heart contractility reflected modifications of SR function, whose reduction after 1 month of overload was followed by a gradual recovery. A decrease in SERCA2a protein and mRNA content was shown from 1 month and remained for the following 2 months. Phospholamban content and its phosphorylation status were not modified. Acylphosphatase was unchanged at 1 month, but at 2 months this enzyme exhibited an increased activity, protein and mRNA expression. Morphological alterations consisting of the cytoskeletal architectures, intermyofibrillar oedema, swollen mitochondria and abnormality of the membrane system (T-tubule and SR cisternae) were particularly evident after 1 month but almost disappeared after 3 months. These results suggest that our overloaded hearts underwent a substantial recovery of their structural and biochemical properties at 3 months after surgery. A possible involvement of acylphosphatase in the modification of SR function is discussed.
Nediani
C
C
Department of Biochemical Sciences, Viale Morgagni 50, 50134 Florence, Italy.
Formigli
L
L
Perna
A M
AM
Pacini
A
A
Ponziani
V
V
Modesti
P A
PA
Ibba-Manneschi
L
L
Zecchi-Orlandini
S
S
Fiorillo
C
C
Cecchi
C
C
Liguori
P
P
Fratini
G
G
Vanni
S
S
Nassi
P
P
D017766:Acid Anhydride Hydrolases / Q000378:metabolism*; D000818:Animals; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D004452:Echocardiography; D006321:Heart / Q000503:physiopathology*; D006439:Hemodynamics; D006940:Hyperemia / Q000473:pathology* / Q000503:physiopathology*; D008854:Microscopy, Electron; D009206:Myocardium / Q000201:enzymology / Q000473:pathology*; D012519:Sarcoplasmic Reticulum / Q000201:enzymology*; D013552:Swine; D000097024:Acylphosphatase
D017766:Acid Anhydride Hydrolases; D000252:Calcium-Transporting ATPases; D000097024:Acylphosphatase