Service de Physiologie et d'Explorations Fonctionnelles, Nouvel Hôpital Civil, Hôpitaux Universitaires de Strasbourg, Strasbourg, France.
J Appl Physiol (1985). 2013 Jan 15;114(2):172-9. doi: 10.1152/japplphysiol.00239.2012. Epub 2012 Oct 25.
Brain natriuretic peptide (BNP) reduces the extent of myocardial infarction. We aimed to determine whether BNP may reduce skeletal muscle mitochondrial dysfunctions and oxidative stress through mitochondrial K(ATP) (mK(ATP)) channel opening after ischemia-reperfusion (IR). Wistar rats were assigned to four groups: sham, 3-h leg ischemia followed by 2-h reperfusion (IR), pretreatment with BNP, and pretreatment with 5-hydroxydecanoic acid, an mK(ATP) channel blocker, before BNP. Mitochondrial respiratory chain complex activities of gastrocnemius muscles were determined using glutamate-malate (V(max)), succinate (V(succ)), and N,N,N',N'-tetramethyl-p-phenylenediamine dihydrochloride ascorbate (V(TMPD/asc)). Apoptosis (Bax-to-Bcl2 mRNA ratio and caspase-3 activity) and oxidative stress (dihydroethidium staining) were also assessed. Compared with the sham group, IR significantly decreased V(max), reflecting complex I, II, and IV activities (-36%, 3.7 ± 0.3 vs. 5.8 ± 0.2 μmol O(2)·min(-1)·g dry wt(-1), P < 0.01), and V(TMPD/asc), reflecting complex IV activity (-37%, 8.6 ± 0.8 vs. 13.7 ± 0.9 μmol O(2)·min(-1)·g dry wt(-1), P < 0.01). IR increased Bax-to-Bcl2 ratio (+57%, 1.1 ± 0.1 vs. 0.7 ± 0.1, P < 0.05) and oxidative stress (+45%, 9,067 ± 935 vs. 6,249 ± 723 pixels, P > 0.05). BNP pretreatment reduced the above alterations, increasing V(max) (+38%, P < 0.05) and reducing Bax-to-Bcl2 ratio (-55%, P < 0.01) and oxidative stress (-58%, P < 0.01). BNP protection against deleterious IR effects on skeletal muscles was abolished by 5-hydroxydecanoic acid. Caspase-3 activities did not change significantly. Conversely, BNP injected during ischemia failed to protect against muscle injury. In addition to maintaining the activity of mitochondrial respiratory chain complexes and possibly decreasing apoptosis, pretreatment with BNP protects skeletal muscle against IR-induced lesions, most likely by decreasing excessive production of radical oxygen species and opening mK(ATP) channels.
脑利钠肽（BNP）可减轻心肌梗死的程度。我们旨在确定 BNP 是否可以通过缺血再灌注（IR）后线粒体 KATP（mKATP）通道的开放来减轻骨骼肌线粒体功能障碍和氧化应激。将 Wistar 大鼠分为四组：假手术组、3 小时腿部缺血后再灌注 2 小时（IR）组、BNP 预处理组和 BNP 预处理前用 5-羟基癸酸（mKATP 通道阻滞剂）预处理组。使用谷氨酸-苹果酸（V（max））、琥珀酸（V（succ））和 N，N，N'，N'-四甲基-p-苯二胺二盐酸盐抗坏血酸（V（TMPD/asc））测定比目鱼肌线粒体呼吸链复合物的活性。还评估了细胞凋亡（Bax-to-Bcl2mRNA 比值和 caspase-3 活性）和氧化应激（二氢乙啶染色）。与假手术组相比，IR 显著降低了 V（max），反映了复合物 I、II 和 IV 的活性（-36％，3.7 ± 0.3 与 5.8 ± 0.2 μmol O2·min-1·g 干重-1，P <0.01），以及 V（TMPD/asc），反映了复合物 IV 的活性（-37％，8.6 ± 0.8 与 13.7 ± 0.9 μmol O2·min-1·g 干重-1，P <0.01）。IR 增加了 Bax-to-Bcl2 比值（+57％，1.1 ± 0.1 与 0.7 ± 0.1，P <0.05）和氧化应激（+45％，9067 ± 935 与 6249 ± 723 像素，P > 0.05）。BNP 预处理可减轻上述变化，增加 V（max）（+38％，P <0.05）并降低 Bax-to-Bcl2 比值（-55％，P <0.01）和氧化应激（-58％，P <0.01）。5-羟基癸酸可消除 BNP 对骨骼肌有害的 IR 作用的保护作用。半胱天冬酶-3 活性没有明显变化。相反，BNP 在缺血期间注射不能保护肌肉免受损伤。除了维持线粒体呼吸链复合物的活性并可能减少细胞凋亡外，BNP 预处理还可以通过减少活性氧物质的过度产生和打开 mKATP 通道来保护骨骼肌免受 IR 诱导的损伤。
