THE EFFECT OF PH ON THE TRANSIENT-STATE KINETICS OF CA2+-MG2+-ATPASE OF CARDIAC SARCOPLASMIC-RETICULUM - A COMPARISON WITH SKELETAL SARCOPLASMIC-RETICULUM
THE EFFECT OF PH ON THE TRANSIENT-STATE KINETICS OF CA2+-MG2+-ATPASE OF CARDIAC SARCOPLASMIC-RETICULUM - A COMPARISON WITH SKELETAL SARCOPLASMIC-RETICULUM
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DOI：
10.1161/01.res.50.2.310
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发表时间：
1982-01-01
影响因子：
20.1
通讯作者：
SCHWARTZ, A
中科院分区：
文献类型：
--
作者：
MANDEL, F;KRANIAS, EG;SCHWARTZ, A
pH值对肌浆网（SR） Ca2+-Mg2+依赖性atp酶的影响用快速混合猝流仪进行了研究，该仪器能够在4 ms内测量磷酸化和去磷酸化。磷酸化中间体（E .apprx.）的形成和分解速率。研究了Ca2+-Mg2+-ATPase在7.6 ~ 6.0 pH范围内的P)。在pH 6.8时，预载Ca的心脏肌浆网和骨骼肌浆网Ca2+-Mg2+- atp酶磷酸化中间体的形成速率是相同的（t1/2 = 10 ms），但随着pH的降低而降低。酸性pH值（6.0）对心肌肌浆网（t1/2 = 47 ms）的影响比骨骼肌肌浆网（t1/2 = 17 ms）更明显，这与酸中毒对心肌的影响比骨骼肌更明显的研究结果一致。此外，pH值的降低会导致E .apprx速率的降低。P分解步骤（SR反应序列中最慢的步骤）。E .apprx。pH为6.8时，心脏和骨骼SR的P分解半衰期分别为97和77 ms。pH为6.0时，心脏SR和骨骼SR的半衰期分别延长至136 ms和178 ms。
The effect of pH on the Ca2+-Mg2+-dependent ATPase of sarcoplasmic reticulum (SR) was investigated with a rapid mixing quench-flow apparatus capable of measuring phosphorylation and dephosphorylation at times as rapid as 4 ms. The rates of formation and decomposition of the phosphorylated intermediate (E .apprx. P) of the Ca2+-Mg2+-ATPase were studied in the pH range between 7.6 and 6.0. At pH 6.8, the rates of formation of the phosphorylated intermediate of the Ca2+-Mg2+-ATPase of sarcoplasmic reticulum are the same (t1/2 = 10 ms) for cardiac [dog] and skeletal [rabbit] sarcoplasmic reticulum preloaded with Ca, but decrease as the pH is lowered. The effect of acid pH (6.0) is more pronounced for cardiac sarcoplasmic reticulum (t1/2 = 47 ms) than for skeletal sarcoplasmic reticulum (t1/2 = 17 ms), in agreement with studies showing that acidosis has a more pronounced effect on cardiac muscle than on skeletal muscle. In addition, a decrease in pH results in a decrease in the rate of the E .apprx. P decomposition step (the slowest step in the SR reaction sequence). The E .apprx. P decomposition half-lives were 97 and 77 ms, respectively, for cardiac and skeletal SR at pH 6.8. At pH 6.0, the half-lives were increased to 136 and 178 ms for cardiac and skeletal SR, respectively.