Tolerance of myocardium of aged animals to repeated oxygen deficiency.
Hemodynamic and metabolic effects of three times 4 min of oxygen deficiency were investigated in 18-month-old rats in comparison to 4-month-old Wistar rats. Left-ventricular isovolumic-pressure-generating capacity and dp/dtmax during isovolumic conditions and hemodynamic indices during intact circulation were determined in open-chest rats. Additionally, high-energy phosphates were measured at the end of the experiments after 20 min of postasphyxial recovery. Older rats had a significantly reduced isovolumic left-ventricular pressure generating capacity (236 +/- 9 vs 269 +/- 5 mm Hg; p less than 0.05) and a low cardiac index (55 +/- 9 vs 117 +/- 8 ml x min-1 x kg-1). The effects of the oxygen deficiency were comparable in both groups. The isovolumic pressure generating capacity was reduced for 11% vs 14%, and dp/dtmax for 13% vs 13%. The myocardial ATP-content was also decreased for the same extent in both groups (0.6 vs 1.0 mumol/gww). Both hemodynamic and biochemical results indicate that aged myocardium does not have a reduced tolerance to repeated periods of oxygen deficiency.
Hoffmeister
H M
HM
Medical Hospital, Dept. III, University of Tübingen, FRG.
Seipel
L
L
D000227:Adenine Nucleotides / Q000032:analysis; D000375:Aging / Q000378:metabolism*; D000818:Animals; D004195:Disease Models, Animal; D006439:Hemodynamics; D000860:Hypoxia / Q000378:metabolism*; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D000227:Adenine Nucleotides