P1833The c-fos mRNA expression reveals persistent myocardial stretch in the right ventricle during asphyxiated cardiac arrest

Abstract

Abstract Background Donation after circulatory death (DCD) heart transplantation has been debated over the past decades because of the shortage of donor. The right ventricular dysfunction is one of the remaining problems for clinical implication of DCD heart transplantation. DCD hearts suffering from the volume overload have a potential to aggravate the right ventricular dysfunction after heart transplantation. The c-fos mRNA is one of the “immediate” response genes to mechanical stresses, such as myocardial cell stretch, without neural and humoral factors. In this study, we assessed myocardial stretch during asphyxiated cardiac arrest using c-fos mRNA expression. Purpose The purpose of this study is to reveal the impact of right ventricular volume overload during asphyxiated cardiac arrest. Methods Male Wistar rats (8 weeks of age, n=18) were anesthetized with paralyzed ventilation. The trachea was dissected and ligated to initiate asphyxiation. Hearts were harvested at 3 time points: 0, 15 and 30 minutes after termination of the ventilation. Free walls of right and left ventricle were sectioned and immersed in RNA stabilization solution as soon as possible. Total RNA was extracted from these tissues using a guanidine thiocyanate-phenol-chloroform method and cDNA was synthesized using a reverse transcriptase. Next, we measured the quantified expression level by using the droplet digital PCR method with a probe and primers for c-fos gene. Expression of c-fos level was divided by extracted TATA binding protein (TBP) level as a control marker, the ratio of c-fos and TBP was used in analysis. Results In the left ventricle, the expression of c-fos rapidly increased by 15 minutes (0.81±0.24 (c-fos/TBP), p<0.05 by one-way ANOVA followed by the Dunnett's test) compared to at 0 minutes (0.21±0.06), but the expression level recovered to the baseline level at 30 minutes after termination of the ventilation (0.19±0.03). On the other hand, in the right ventricle, the c-fos expression was gradually elevated and peaked at 30 minutes (0.88±0.20, p<0.05 by the Dunnett's test) compared to at 0 minutes (0.22±0.05). Conclusion These results suggest that the volume overload to the right ventricle during asphyxiated cardiac arrest prolongs compared to that to the left ventricle, which may cause the right ventricular dysfunction after DCD heart transplantation.