| Project/Area Number |
07671446
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Thoracic surgery
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| Research Institution | ASAHIKAWA MEDICAL COLLEGE |
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Principal Investigator |
YAMAMOTO Hiroshi ASAHIKAWA MEDICAL COLLEGE FIRST DEPARTMENT OF SURGERY LECTURER, 医学部, 講師 (10270795)
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| Co-Investigator(Kenkyū-buntansha) |
GOH Kazutomo ASAHIKAWA MEDICAL COLLEGE DEPARTMENT OF EMERGENCY ASSOCIATE PROFESSOR, 医学部, 助教授 (00234964)
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| Project Period (FY) |
1995 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1997: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1996: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1995: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Keywords | OPEN HEART SURGERY / ISCHEMIA / REPERFUSION / HIGH K^+ BLOOD CARDIOPLEGIA / MYOCARDIAL PROTECTION / CATION MOVEMENT / MYOCARDIAL OXYGEN CONSUMPTION / Na^+ / K^+ PUMP / K^+ MOVEMENT EFFICIENCY / 心筋酸素摂取率 |
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| Research Abstract |
Myocardial ischemia results in intracellular ionic imbalance (Na<@D1+@>D1 overload ; K<@D1+@>D1 loss). We hypothesize that warm oxygenated blood cardioplegia (warm OBC) in the post-ischemic myocardium, incresing myocardial oxygen consumption (VO<@D22@>D2), may enhance Na<@D1+@>D1/K<@D1+@>D1 pump activity, which could contribute to recovery from the intracellular ionic imbalance. To test this, we determined temperature dependency of Na<@D1+@>D1/K<@D1+@>D1 pump activity and investigated the relationship between VO<@D22@>D2 and cation movement during warm OBC in cardiac surgery. Methods : (A) ouabain sensitive current (Ip) was measured at 18ﾟ, 28ﾟ, and 28ﾟC by whole-cell clamp technique (ramp : +50--130 mV) using Guinea-pig ventricular myocytes. (B) 44 patients undergoing cardiac surgery received OBC every 30 min at 18ﾟC and finally at 35ﾟ-37ﾟC (Na<@D1+@>D1 : 134.8(]SY.+-。[)0.4 ; K<@D1+@>D1 : 18.7(]SY.+-。[)0.1 mmol/L). During the infusion of the final warm OBC,the coronary effluent was sa
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mpled (5-8 different points/patient) from the coronary sinus (CS). Na<@D1+@>D1 or K<@D1+@>D1 movement was assessed by its concentration difference ( [cation] <@D2CS@>D2 minus [cation] <@D2OBC@>D2) and VO<@D22@>D2 by the difference of oxygen content between the OBC solution and the CS effluent. Cation movement efficiency (Ek, K<@D1+@>D1 movement per unit volume of VO<@D22@>D2) was assessed by calculating a slope using linear regression analysis in the K<@D1+@>D1 movement-VO<@D22@>D2 relationship. Results : (A) Ip was greater at 37ﾟC than at 18ﾟC (114.3(]SY.+-。[)17.2 vs 22.7(]SY.+-。[)1.2 pA at -40 mV,respectively). (B) The greatre VO<@D22@>D2 was associated with the greater positive value of the [Na<@D1+@>D1] difference and the greater negative value of the [K<@D1+@>D1] difference, suggesting energy dependent transsarcolemmal cation movement(outward Na<@D1+@>D1 ; inward K<@D1+@>D1)during the final warm OBC.Ek (0.227-0.019 mmol/ml O<@D22@>D2) decreased with prologation of the ischemic period (23-214 min). Conclusion : There may be energy dependent cation movement during oxygenated cardioplegia, contributing to recovery of the myocardium from the intracellular Na<@D1+@>D1 overload and K<@D1+@>D1 loss. Prolongation of the ischemic period might reduce the effeciency between myocardial oxygen consumption and cation movement. Less
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