| Project/Area Number |
03670449
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
Circulatory organs internal medicine
|
|---|
| Research Institution | Osaka University |
|---|
Principal Investigator |
HORI Masatsugu OSAKA UNIVERSITY MEDICAL SCHOOL ASSISTANT PROFESSOR, 医学部, 助手 (20124779)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
FUJIMOTO Masao YAMASA CORPORATION LABORATORY CHIEF INVESTIGATOR, 研究員
KORETSUNE Yukihiro OSAKA UNIVERSITY MEDICAL SCHOOL ASSISTANT PROFESSOR, 医学部, 助手 (50243217)
KITAKAZE Masafumi OSAKA UNIVERSITY HOSPITAL CLINICAL FELLOW, 医学部附属病院, 医員
KUZUYA Tsunehiko OSAKA UNIVERSITY MEDICAL SCHOOL ASSOSIATE PROFESSOR, 医学部, 助教授 (80150340)
|
|---|
| Project Period (FY) |
1991 – 1992
|
| Project Status |
Completed (Fiscal Year 1992)
|
| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1992: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1991: ¥1,200,000 (Direct Cost: ¥1,200,000)
|
|---|
| Keywords | adenosine / ischemia / reperfusion / alpha1-adrenoceptorstimulation / myocardial stunning / 心筋スタニング / 再潅流障害 / α1ーアドレナリン受容体 / プロプラノロ-ル / ヨヒンビン |
|---|
| Research Abstract |
This study was undertaken to elucidate whether alpha_1-adrenoceptor activity is beneficial for contractile dysfunction during ischemia and reperfusion in open-chest dogs. Myocardial ischemia increased release of adenosine with reductions of coronary blood flow and fractional shortening. Prazosin (4 ug/kg/min, ic) further deteriorated contractile dysfunction with attenuated adenosine release and coronary blood flow. In turn, methoxamine (1ug/kg/min, ic), which does not affect basal coronary vascular tones, increased both adenosine release and coronary blood flow during ischemia and improved contractile function. This augmentation of adenosine release and coronary blood flow due to methoxamine increased fractional shortening, which was inhibited by 8-phenyltheophylline. These results indicate that alpha_1- adrenoceptor activity increases adenosine release during myocardial ischemia and attenuates contractile dysfunction.
Furthermore, we examined the effects of alpha_1-adrenoceptor activity on myocardial stunning assessed at 3 hours after the onset of reperfusion followed by 15 min of complete occlusion of the left anterior descending coronary artery. Prazosin attenuated fractional shortening (12.7* 0.6 vs. 6.9 * 0.4 % with prazosin treatment, p<0.001). On the other hand, methoxamine attenuated contractile dysfunction. Both adenosine release and hyperemic coronary flow response during early reperfusion period were attenuated in the prazosin-treated group, and both were enhanced in the methoxamine-treated group. Thus we conclude that (1) alpha_1-adrenoceptor activity improves myocardial function during ischemia and reperfusion and (2) its cellular mechanism is due to enhanced adenosine release by alpha_1-adrenoceptor activity.
|
