Adaptation to chronic hypoxia confers tolerance to subsequent myocardial ischemia by increased nitric oxide production.
Chronic exposure to hypoxia from birth increased the tolerance of the rabbit heart to subsequent ischemia compared with age-matched normoxic controls. The nitric oxide donor GSNO increased recovery of post-ischemic function in normoxic hearts to values not different from hypoxic controls, but had no effect on hypoxic hearts. The nitric oxide synthase inhibitors L-NAME and L-NMA abolished the cardioprotective effect of hypoxia. Message and catalytic activity for constitutive nitric oxide synthase as well as nitrite, nitrate, and cGMP levels were elevated in hypoxic hearts. Inducible nitric oxide synthase was not detected in normoxic or chronically hypoxic hearts. Increased tolerance to ischemia in rabbit hearts adapted to chronic hypoxia is associated with increased expression of constitutive nitric oxide synthase.
Department of Cardiothoracic Surgery, Medical College of Wisconsin, Milwaukee 53226, USA. jbaker@mcw.edu
J E
JE
Baker
P
P
Holman
B
B
Kalyanaraman
O W
OW
Griffith
K A
KA
Pritchard
D000222:Adaptation, Physiological / Q000502:physiology*; D000818:Animals; D002908:Chronic Disease; D006152:Cyclic GMP / Q000378:metabolism; D000860:Hypoxia / Q000378:metabolism / Q000503:physiopathology*; D017202:Myocardial Ischemia / Q000378:metabolism / Q000503:physiopathology*; D009206:Myocardium / Q000378:metabolism; D009566:Nitrates / Q000378:metabolism; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D009573:Nitrites / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits
D009566:Nitrates; D009573:Nitrites; D012333:RNA, Messenger; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D006152:Cyclic GMP