Preconditioning with heat shock further improved functional recovery in young adult but not in middle-aged rat hearts.
Ischemic preconditioning (PC) improves post-ischemic function, and heat shock (HS) mimics delayed PC in young animals. However, PC is not protective and the consequences of HS are not known in the aging hearts. This report examines the efficacy of HS and its synergy with PC in the middle-aged rat hearts. Hearts from 12- or 50-week-old rats were subjected to PC before 25 min ischemia followed by 30 min reperfusion 48 h after HS. HS induced HS proteins (HSP) in both age groups but that PC and HS translocated PKC-alpha and -delta only in young rats. The beneficial effects of HS and PC were additive and enhanced protein kinase C (PKC) translocation in young rats. However, neither HS alone nor in combination with PC conferred any functional advantage or accelerated PKC translocation in old rats. Similarly neither HS alone nor in combination with PC restore PC effects in old rats with impaired PKC activation, despite the induction of HSP, indicating that induction of HSP is insufficient for cytoprotection.
Honma
Yukako
Y
Division of Geriatric Medicine, Department of Internal Medicine, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-Ku, Tokyo 160-8582, Japan.
Tani
Masato
M
Yamamura
Ken
K
Takayama
Michiyo
M
Hasegawa
Hiroshi
H
D000375:Aging / Q000502:physiology*; D000818:Animals; D015153:Blotting, Western; D055551:HSP27 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins / Q000032:analysis; D006321:Heart / Q000502:physiology*; D006360:Heat-Shock Proteins; D006358:Hot Temperature; D019157:Ischemic Preconditioning, Myocardial; D008297:Male; D009363:Neoplasm Proteins / Q000032:analysis; D011493:Protein Kinase C / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D020127:Recovery of Function; D012769:Shock; D016277:Ventricular Function, Left / Q000502:physiology; D038205:beta-Crystallin A Chain / Q000032:analysis
D055551:HSP27 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C486114:Hspb1 protein, rat; D009363:Neoplasm Proteins; D038205:beta-Crystallin A Chain; D011493:Protein Kinase C