Tani M, Neely J R
Weis Center for Research, Geisinger Clinic, Danville, Pennsylvania 17822.
Am J Physiol. 1990 Apr;258(4 Pt 2):H1025-31. doi: 10.1152/ajpheart.1990.258.4.H1025.
Mechanisms of the protective effects of low Ca2+ (0.15 mM) and/or high K+ (20 mM) concentrations in the buffer on reperfusion injury were investigated. Intracellular Na+ (Nai+) increased fourfold during 25 min of ischemia. When hearts were reperfused with the standard buffer (1.25 mM Ca2+, 5.9 mM K+), Nai+ increased further during the 1st 2 min (5-fold) and then declined by 30% at 10 min of reperfusion. Ca2+ uptake increased 6- and 12-fold at 10 and 30 min of reperfusion, respectively. Function, which was assessed as the product of developed pressure and heart rate, recovered to 45% of the preischemic value and end-diastolic pressure was elevated (EDP: 31 mmHg). Reperfusion for 10 min with low Ca2+ buffer abolished the increase in Ca2+ uptake during this period, but it increased 10-fold when the perfusate was switched back to the standard buffer. Accelerated Ca2+ influx at this time was probably through Na(+)-Ca2+ exchange because Nai+ did not decline during low Ca2+ reperfusion. Elevation of EDP was suppressed (12 mmHg), but development of pressure did not increase. Reperfusion for 10 min with high K+ buffer accelerated the decline in Nai+ by 70% and reduced the increase in Ca2+ uptake (8-fold). Recovery of function improved (67%, EDP: 18 mmHg). Further improvement in function (78%, EDP: 10 mmHg) was obtained along with less Ca2+ uptake (7-fold) when low Ca2+ and high K+ were combined. Recovery of energy metabolites at 10 and 30 min of reperfusion was not different among the groups.(ABSTRACT TRUNCATED AT 250 WORDS)
研究了缓冲液中低钙（0.15 mM）和/或高钾（20 mM）浓度对再灌注损伤的保护作用机制。在25分钟的缺血期间，细胞内钠离子（Nai+）增加了四倍。当心脏用标准缓冲液（1.25 mM钙，5.9 mM钾）进行再灌注时，Nai+在最初2分钟内进一步增加（5倍），然后在再灌注10分钟时下降30%。在再灌注10分钟和30分钟时，钙摄取分别增加了6倍和12倍。功能通过收缩压和心率的乘积来评估，恢复到缺血前值的45%，舒张末期压力升高（EDP：31 mmHg）。用低钙缓冲液再灌注10分钟消除了在此期间钙摄取的增加，但当灌注液换回标准缓冲液时，钙摄取增加了10倍。此时加速的钙内流可能是通过钠-钙交换，因为在低钙再灌注期间Nai+没有下降。EDP的升高受到抑制（12 mmHg），但压力的升高没有增加。用高钾缓冲液再灌注10分钟使Nai+的下降加速了70%，并减少了钙摄取的增加（8倍）。功能恢复得到改善（67%，EDP：18 mmHg）。当低钙和高钾联合使用时，功能进一步改善（78%，EDP：10 mmHg），同时钙摄取减少（7倍）。在再灌注10分钟和30分钟时，各组能量代谢产物的恢复没有差异。（摘要截断于250字）
