Changes in force and calcium sensitivity in the developing avian heart.
Changes in force and calcium sensitivity in the developing avian heart.
复制标题
发育中的禽类心脏的力和钙敏感性的变化。
DOI：
10.1139/y91-251
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发表时间：
1991
影响因子：
2.1
通讯作者：
Nosek,TM
中科院分区：
文献类型：
--
作者：
Godt,RE;Fogaça,RT;Nosek,TM
本研究的目的是描述完整的和化学剥皮的鸡心脏肌肉的收缩特性的发展，并将这些特性与其他报道的哺乳动物心脏的发展进行比较。在胚胎第7天至雏鸡（孵化后7周）左心室解剖小小梁。在所有年龄段，增加细胞外钙（0.45-3.6 mM）逐渐增加电刺激小梁的抽动力。1.8 mM细胞外钙的抽动力，按横截面积归一化，在孵化后1天达到最大值，在孵化后3周保持不变，但在孵化后7周下降。Triton X-100洗剂化学剥皮小梁的最大钙活化力在孵化前2天达到最大值，直到孵化后7周变化不显著。在研究的年龄中，1.8 mM钙的平均抽动力在剥皮后最大钙激活力的26%至66%之间，表明正常林格肌抽动时收缩装置未完全激活。在剥皮小梁中，胚胎的收缩器对钙的敏感性高于青年成人。这些钙敏感性的年龄依赖性变化与肌钙蛋白t的同型转换有关。pH从7.0降至6.5时，与胚胎心脏相比，年轻成人心脏皮肤小梁的收缩器钙敏感性降低的程度更大。这种酸中毒易感性的改变暂时与肌钙蛋白i的同型型转换有关。此外，年轻人心脏小梁的最大钙活化力随pH值的降低也更大。由此可见，鸡胚心脏的收缩器官对酸中毒的抑制作用的敏感性低于成体心脏。这些钙敏感性的发育变化类似于其他哺乳动物心脏的报道。关键词：肌肉收缩，心脏发育，酸中毒，鸡，收缩蛋白。
The aim of this study was to characterize the development of the contractile properties of intact and chemically skinned muscle from chicken heart and to compare these characteristics with those of developing mammalian heart reported by others. Small trabeculae were dissected from left ventricles of Arbor Acre chickens between embryonic day 7 and young adulthood (7 weeks post-hatching). At all ages, increasing extracellular calcium (0.45–3.6 mM) progressively increased twitch force of electrically stimulated trabeculae. Twitch force at 1.8 mM extracellular calcium, normalized to cross-sectional area, increased to a maximum at 1 day post-hatching, remained constant through 3 weeks post-hatching, but then decreased at 7 weeks post-hatching. The maximal calcium-activated force of trabeculae chemically skinned with Triton X-100 detergent increased to a maximum 2 days before the time of hatching and was not significantly changed up to 7 weeks post-hatching. Over the ages studied, average twitch force in 1.8 mM calcium was between 26 and 66% of maximal calcium-activated force after skinning, suggesting that the contractile apparatus is not fully activated during the twitch in normal Ringer. In skinned trabeculae, the calcium sensitivity of the contractile apparatus was higher in the embryo than in the young adult. These age-dependent changes in calcium sensitivity are correlated with isoform switching in troponin T. A decrease in pH from 7.0 to 6.5 decreased the calcium sensitivity of the contractile apparatus to a greater degree in skinned trabeculae from young adult hearts than in those from embryonic hearts. This change in susceptibility to acidosis is temporally associated with isoform switching in troponin I. Moreover, the decrease in maximal calcium-activated force with pH was also greater in trabeculae from young adult heart. Thus the contractile apparatus of embryonic chicken heart is less sensitive to the depressant effects of acidosis than that of the adult heart. These developmental changes in calcium sensitivity are analogous to those reported by others in mammalian heart.Key words: muscle contraction, heart development, acidosis, chicken, contractile proteins.