['We aimed to determine the impact of aging on ischemic acute kidney injury, especially in terms of the pathological mechanisms of kidney and heart crosstalk.', 'The effects of 45 min of unilateral ischemic reperfusion (IR) of the renal artery on the contralateral kidney and heart were histologically assessed in 7- and 40-week-old SD rats after 7 days.', 'Glomerular sclerosis, interstitial fibrosis and numbers of ED1 cells were significantly increased in the contralateral kidneys of the 40-, but not the 7-week-old rats. The numbers of ED1 cells in the heart significantly and similarly increased in both groups, but reactive fibrosis after IR was significant only in the 40-week-old rats. The exaggerated profibrotic response induced by aging seemed to be closely associated with the increased number of ED1 cells in the affected area.'] Does ischemia/reperfusion of unilateral kidney exaggerate aging-induced damage to the heart and contralateral kidney?