Gene expression of proteins influencing the calcium homeostasis in patients with persistent and paroxysmal atrial fibrillation

Objective: Persistent atrial fibrillation (AF) results in an impairment of atrial function. In order to elucidate the mechanism behind this phenomenon , we investigated the gene expression of proteins influencing calcium handl ing. Methods: Right atrial appendages were obtained from eight patients wit h paroxysmal AF, ten with persistent AF (>8 months) and 18 matched controls in sinus rhythm. All controls underwent coronary artery bypass grafting, w hereas most AF patients underwent Cox's MAZE surgery (n=12). All patients h ad a normal left ventricular function. Total RNA was isolated and reversely transcribed into cDNA. In a semi-quantitative polymerase chain reaction th e cDNA of interest and of glyceraldehyde-3-phosphate dehydrogenase were coa mplified and separated by ethidium bromide-stained gel electrophoresis. Slo t blot analysis was performed to study protein expression. Results: L-type calcium channel alpha(1) and sarcoplasmic reticulum Ca2+-ATPase mRNA (-57%, p=0.01 and -28%, p=0.04, respectively) and protein contents (-43%, p=0.02 and -28%, p=0.04, respectively) were reduced in patients with persistent AF compared to the controls, mRNA contents of phospholamban, ryanodine recept or type 2 and sodium/calcium exchanger were comparable. No changes were obs erved in patients with paroxysmal AF. Conclusions: Alterations in gene expr ession of proteins involved in the calcium homeostasis occur only in patien ts with long-term persistent AF. In the absence of underlying heart disease , the changes are rather secondary than primary to AF. (C) 1999 Elsevier Sc ience B.V. All rights reserved.