title: Cardiac effects of acute exhaustive exercise in a rat model.
abstract: BACKGROUND
  The role of physical exercise in the prevention and treatment of cardiovascular diseases has been well described, however, elevations in cardionecrotic biomarkers after prolonged exercise (i.e. ultramarathon running) were observed. We aimed at understanding the biochemical, molecular biological, structural and functional alterations in the heart after exhaustive exercise in a rat model.
  
  
  METHODS
  Rats of the exercise group were forced to swim for 3h with 5% body weight (workload) attached to the tail, control rats were taken into the water for 5min. After a 2-hour recovery period we performed left ventricular (LV) pressure-volume analysis to investigate LV function and mechanoenergetics. Additionally, blood and myocardium samples were harvested for biochemical and histological examinations. Gene expression changes were detected by qRT-PCR.
  
  
  RESULTS
  When compared to controls, elevated plasma levels of cardiac troponin T and creatine kinase were detected after exhaustive exercise. Histological analysis showed sporadic fragmentation of myocardial structure and leukocyte infiltration in the exercised group. We observed increased end-systolic volume, decreased ejection fraction, impaired contractility (preload recruitable stroke work) and mechanoenergetics (ventriculoarterial coupling, mechanical efficiency) of LV after exercise. Myocardial expression of major antioxidant enzymes was increased along with increased myocardial nitro-oxidative stress. Bax/Bcl-2 ratio and TUNEL staining showed enhanced apoptotic signaling. Exhaustive exercise also resulted in the dysregulation of the matrix metalloproteinase system.
  
  
  CONCLUSIONS
  Excessive physical activity has an adverse effect on the heart. The observed functional impairment is associated with increased nitro-oxidative stress, enhanced apoptotic signaling and dysregulation of the matrix metalloproteinase system after exhaustive exercise.
authors.affiliation: Heart and Vascular Center, Semmelweis University, Városmajor u. 68, 1122 Budapest, Hungary. Electronic address: o.attilio@gmail.com.
authors.forename: Attila
authors.initials: A
authors.lastname: Oláh
authors.affiliation: Heart and Vascular Center, Semmelweis University, Városmajor u. 68, 1122 Budapest, Hungary.
authors.forename: Balázs Tamás
authors.initials: BT
authors.lastname: Németh
authors.affiliation: Heart and Vascular Center, Semmelweis University, Városmajor u. 68, 1122 Budapest, Hungary.
authors.forename: Csaba
authors.initials: C
authors.lastname: Mátyás
authors.affiliation: Institute of Human Physiology and Clinical Experimental Research, Semmelweis University, Tűzoltó u. 37-47, 1094 Budapest, Hungary.
authors.forename: Eszter Mária
authors.initials: EM
authors.lastname: Horváth
authors.affiliation: Heart and Vascular Center, Semmelweis University, Városmajor u. 68, 1122 Budapest, Hungary.
authors.forename: László
authors.initials: L
authors.lastname: Hidi
authors.affiliation: Heart and Vascular Center, Semmelweis University, Városmajor u. 68, 1122 Budapest, Hungary.
authors.forename: Ede
authors.initials: E
authors.lastname: Birtalan
authors.affiliation: Heart and Vascular Center, Semmelweis University, Városmajor u. 68, 1122 Budapest, Hungary.
authors.forename: Dalma
authors.initials: D
authors.lastname: Kellermayer
authors.affiliation: Heart and Vascular Center, Semmelweis University, Városmajor u. 68, 1122 Budapest, Hungary.
authors.forename: Mihály
authors.initials: M
authors.lastname: Ruppert
authors.affiliation: Heart and Vascular Center, Semmelweis University, Városmajor u. 68, 1122 Budapest, Hungary.
authors.forename: Gergő
authors.initials: G
authors.lastname: Merkely
authors.affiliation: Department of Cardiac Surgery, University of Heidelberg, 2. OG. INF 326, 69120 Heidelberg, Germany.
authors.forename: Gábor
authors.initials: G
authors.lastname: Szabó
authors.affiliation: Heart and Vascular Center, Semmelweis University, Városmajor u. 68, 1122 Budapest, Hungary.
authors.forename: Béla
authors.initials: B
authors.lastname: Merkely
authors.affiliation: Heart and Vascular Center, Semmelweis University, Városmajor u. 68, 1122 Budapest, Hungary; Department of Cardiac Surgery, University of Heidelberg, 2. OG. INF 326, 69120 Heidelberg, Germany.
authors.forename: Tamás
authors.initials: T
authors.lastname: Radovits
mesh_terms: D000818:Animals; D002318:Cardiovascular Diseases / Q000378:metabolism / Q000503:physiopathology / Q000517:prevention & control*; D004195:Disease Models, Animal; D008297:Male; D032383:Myocytes, Cardiac / Q000378:metabolism* / Q000473:pathology; D018384:Oxidative Stress; D010805:Physical Conditioning, Animal / Q000379:methods*; D005082:Physical Exertion / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D016277:Ventricular Function, Left / Q000502:physiology*
keywords: Cardiac function; Cardiac mechanoenergetics; Exhaustive exercise; Gene expression; Oxidative stress; Pressure-volume analysis