title: Cardiac function in rats selectively bred for low- and high-capacity running.
abstract: Rat genetic models of intrinsic (i.e., untrained) low-capacity runners (LCR) and high-capacity runners (HCR) are being developed by artificial selective breeding for treadmill running. At generation 3, these lines differed in running capacity by 114%. We used generation 3 rats to test the hypotheses that HCR, relative to LCR, have 1) greater isolated cardiac performance and 2) more resistance to myocardial ischemic insult. The LCR ran for 227 +/- 7 m, and the HCR ran 994 +/- 11 m at exhaustion (337% difference, P < 0.001). Isolated heart performance was assessed from cardiac output (CO) generated at constant preload (15 mmHg) and afterload (70 mmHg) using a Langendorff-Neely working heart preparation. CO averaged 33.5 +/- 2.0 ml. min(-1). g(-1) in LCR hearts and 49.9 +/- 1.4 ml. min(-1). g(-1) in HCR hearts (49% difference, P < 0.001). Recovery of CO after 25 min of global ischemia was not different between the lines. These results suggest that 1) increased cardiac performance accounts for part of the difference in running capacity between the lines; and 2) unlike exercise training, genetically determined intrinsic capacity for exercise does not influence the recovery from 25 min of global low-flow cardiac ischemia.
authors.affiliation: Functional Genomics Laboratory, Medical College of Ohio, 3035 Arlington Ave., Toledo, OH 43614-5804, USA.
authors.forename: S O
authors.initials: SO
authors.lastname: Hussain
authors.forename: J C
authors.initials: JC
authors.lastname: Barbato
authors.forename: L G
authors.initials: LG
authors.lastname: Koch
authors.forename: P J
authors.initials: PJ
authors.lastname: Metting
authors.forename: S L
authors.initials: SL
authors.lastname: Britton
mesh_terms: D000818:Animals; D001835:Body Weight; D001947:Breeding; D002302:Cardiac Output / Q000502:physiology; D003326:Coronary Circulation / Q000502:physiology; D006321:Heart / Q000033:anatomy & histology / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D066298:In Vitro Techniques; D008957:Models, Genetic; D017202:Myocardial Ischemia / Q000503:physiopathology; D009929:Organ Size; D010805:Physical Conditioning, Animal / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D012420:Running / Q000502:physiology*; D013045:Species Specificity