Raloxifene improves coronary perfusion, cardiac contractility, and myocardial metabolism in the ischemic heart: role of phosphatidylinositol 3-kinase/Akt pathway.
The purpose of this study is to examine whether raloxifene, one of the selective estrogen receptor modulators, could improve myocardial ischemia and to assess the mechanisms involved. In open-chest beagle dogs anesthetized by intravenous infusion of sodium pentobarbital, the left anterior descending coronary artery (LAD) was perfused from the left carotid artery through an extracorporeal bypass tube. Raloxifene was infused into the LAD through the bypass tube under either ischemic or non-ischemic conditions. In the non-ischemic heart, raloxifene had no effect on coronary blood flow, fractional shortening, and myocardial metabolism. However, raloxifene caused an acute increase in both coronary blood flow and fractional shortening, and also improved myocardial anaerobic metabolism in the ischemic heart. These effects were partially attenuated by pretreatment with either L-NAME or wortmannin and were completely abolished by ICI182780 (an estrogen receptor antagonist) or L-NAME plus charybdotoxin (a blocker of Ca-activated K channels). Raloxifene also increased both Akt activity and the NO level, with these changes being completely abrogated by pretreatment with wortmannin. These results demonstrated that raloxifene improves coronary perfusion, cardiac contractility, and myocardial metabolism by release of NO and opening of Ca-activated K channels in the ischemic heart, and that NO production is mediated by the phosphatidylinositol 3-kinase/Akt pathway.
Ogita
Hisakazu
H
Department of Internal Medicine and Therapeutics, Osaka University Graduate School of Medicine, Osaka, Japan.
Node
Koichi
K
Asanuma
Hiroshi
H
Sanada
Shoji
S
Kim
Jiyoong
J
Takashima
Seiji
S
Minamino
Tetsuo
T
Hori
Masatsugu
M
Kitakaze
Masafumi
M
D000818:Animals; D004285:Dogs; D009200:Myocardial Contraction / Q000187:drug effects* / Q000502:physiology; D015428:Myocardial Reperfusion Injury / Q000188:drug therapy / Q000201:enzymology* / Q000503:physiopathology; D009206:Myocardium / Q000201:enzymology; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D011518:Proto-Oncogene Proteins / Q000502:physiology*; D051057:Proto-Oncogene Proteins c-akt; D020849:Raloxifene Hydrochloride / Q000494:pharmacology* / Q000627:therapeutic use; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D020849:Raloxifene Hydrochloride