1993 Fiscal Year Final Research Report Summary
The Effects of Adenosine and Mg^<2+> on Cardiovascular Dynamics and Cardiac Rhythm
| Project/Area Number |
02454362
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
麻酔学
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| Research Institution | Jichi Medical University |
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Principal Investigator |
SHIMIZU Reiju Dept.of anesthesiology, Professor, 医学部, 教授 (60010253)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAIGAWA Yasushi Dept.of Anesthesiology, Assistant, 医学部, 助手 (40245056)
ISHI Ryosuke Dept.of anesthesiology, Assistant, 医学部, 助手 (50222956)
AKAZAWA Satoshi Dept.of Anesthesiology, Assistant Professor, 医学部, 助教授 (10184079)
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| Project Period (FY) |
1990 – 1992
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| Keywords | Adenosine / Magnesium / Cardiac function / Coronary circulation / Myocardical metabolism / His bundle electrogram / Ischemic heart / Myocardial infarction |
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| Research Abstract |
[Purpose] This study was undertaken to examine the effects of adenosine and MgSO_4 on cardiac function, coronary circulation, myocardial metabolism and the cardiac conduction system and to determine whether these drugs can be used as a choice of deliberate hypotensive agents and also as a choice of therapeutic agents for an ischemic heart.
[Methods] In 35 anesthetized open-chest dogs, blood pressures, cardiac output and coronary artery blood flow, and coronary sinus blood flow were measured by catheter-tipped transducers, electromagnetic flowmeters, and a thermodilution method, respectively. Myocardial metabolic indices were determined by arterial and coronary sinus blood oxygen and lactate contents. The function of the cardiac conduction system was analyzed by recording His bundle electrogram.
[Results] Adenosine produced a decrease in mean arterial pressure and an increase in coronary sinus blood flow with a concomitant decrease in myocardial oxygen consumption (luxury perfusion) in a
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dose-dependent manner at infusion rates of 0.1,0.3,0.5 and 1.0mg・kg^<-1>. MgSO_4 produced dose-dependent decreases in mean arterial pressure, heart rate, and left ventricular contractile and relaxing function without producing luxury perfusion at serum concentrations of 1.5,2.5,4.1 and 7.8mg・dl^<-1>. Adenosine prolonged A-H and S-H conduction times without changing P-A and H-V conduction times during both sinus rhythm and right atrial pacing. MgSO_4 dose-dependently prolonged A-H, S-H and H-V conduction times during both sinus rhythm and right atrial pacing. Both drugs showed no arrhythmogenic effect. MgSO_4 did not worsen the extent of myocardial ischemia induced by coronary artery occlusion. The function of the ischemic left ventricle as a pump was well preserved, because of a decrease in afterload. Coronary blood flow decreased in a parallel with a decrease in myocardial oxygen demand.
[Conclusions] We demonstrated that adenosine and MgSO_4 could be used for deliberate hypotension in a clinical practice and MgSO_4 might exert a protective effect on an ischemic heart without impairing its pump function. Less
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