Mahony L
Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas 75235.
Pediatr Res. 1988 Nov;24(5):639-43. doi: 10.1203/00006450-198811000-00020.
Developmental changes in myocardial function have been described by a number of investigators. To further define the cellular basis for these changes, the present study was designed to characterize age-related changes in Ca2+ transport in sarcoplasmic reticulum (SR) vesicles isolated from six groups of sheep: group (Sp) I (100-105 days gestation), Gp II (128-132 days gestation), Gp III (postnatal, 0-3 days), Gp IV (4 wk), Gp V (8 wk), and Gp VI (maternal sheep). The maximal Ca2+ uptake for vesicles isolated from Gp I-V was significantly (p less than 0.01) decreased as compared to that measured for Gp VI (maternal) vesicles. However, Ca2+-dependent ATP hydrolysis was decreased only in the fetal SR vesicles (Gp I-II). Thus, decreased ATP hydrolysis only partially explained the decreased Ca2+ uptake. In contrast, calculation of apparent Ca2+ pump coupling ratios (mol of Ca2+ transported/mol of ATP hydrolyzed) showed that there was a marked increase in the coupling of Ca2+ transport to ATP hydrolysis during maturation of the heart. Inasmuch as the contractile state of the heart depends on precise regulation of Ca2+ concentration by the SR, these age-related changes in SR function may contribute to developmental changes in myocardial function.
许多研究人员都描述过心肌功能的发育变化。为了进一步明确这些变化的细胞基础，本研究旨在对从六组绵羊分离出的肌浆网（SR）囊泡中与年龄相关的Ca2+转运变化进行表征：第一组（Sp）（妊娠100 - 105天），第二组（Gp II）（妊娠128 - 132天），第三组（Gp III）（出生后0 - 3天），第四组（Gp IV）（4周），第五组（Gp V）（8周），以及第六组（Gp VI）（母羊）。与第六组（母羊）囊泡相比，从第一至五组分离出的囊泡的最大Ca2+摄取量显著降低（p < 0.01）。然而，仅在胎儿SR囊泡（第一至二组）中Ca2+依赖性ATP水解降低。因此，ATP水解降低仅部分解释了Ca2+摄取的降低。相反，表观Ca2+泵偶联比率（转运的Ca2+摩尔数/水解的ATP摩尔数）的计算表明，在心脏成熟过程中Ca2+转运与ATP水解的偶联显著增加。由于心脏的收缩状态取决于SR对Ca2+浓度的精确调节，SR功能的这些与年龄相关的变化可能有助于心肌功能的发育变化。
