Koenig H, Fan C C, Goldstone A D, Lu C Y, Trout J J
Neurology Service, VA Lakeside Medical Center, Chicago, IL 60611.
Circ Res. 1989 Mar;64(3):415-26. doi: 10.1161/01.res.64.3.415.
The androgenic steroid hormone testosterone induced an early (less than 30-60 seconds) stimulation of endocytosis, hexose transport, and amino acid transport, monitored by the temperature-sensitive uptake of horseradish peroxidase, 2-deoxyglucose, and alpha-aminoisobutyrate, respectively, in rat ventricle cubes and acutely isolated ventricular myocytes. This stimulation was time- and concentration-dependent and was maximal at 10(-9) to 10(-8) M testosterone, consistent with androgen-receptor mediation. EGTA (2.5 mM), La3+ (1 mM), and verapamil (100 microM) ablated the hormonal response. The calcium ionophore A23187 (10 microM) induced an acute stimulation of endocytosis, amino acid transport, and hexose transport which was not further increased by testosterone (10(-8) M), suggesting a common effector pathway. Testosterone (10(-8) M) also evoked a rapid (less than 30 seconds) stimulation of 45Ca influx and efflux. Testosterone (10(-8) M) induced a rapid (less than 5 seconds) transient increase in ornithine decarboxylase (ODC) activity peaking (twofold to threefold) at 60 seconds, and an early (15 seconds) transient accumulation of polyamines peaking at 60 seconds in isolated myocytes. The specific, irreversible ODC inhibitor alpha-difluoromethylornithine (DFMO, 5-10 mM) blocked the testosterone-evoked increase in ODC activity and polyamine levels and the stimulation of Ca2+ fluxes, endocytosis, hexose transport, and amino acid transport. Putrescine (0.5-1 mM), the ODC product, reversed DFMO inhibition and restored the increase in polyamines, 45Ca fluxes, and Ca2+-dependent membrane transport processes. These results demonstrate that rapid, transient ODC-regulated polyamine synthesis is essential for androgenic stimulation of Ca2+ fluxes and membrane transport processes in ventricular myocytes. These findings support a model for signal transduction in which newly synthesized polyamines serve as intracellular messengers to regulate transmembrane Ca2+ movements, Ca2+-dependent membrane transport functions, and other Ca2+- and polyamine-sensitive processes in cardiac myocytes.
雄激素类固醇激素睾酮在大鼠心室肌块和急性分离的心室肌细胞中分别通过辣根过氧化物酶、2-脱氧葡萄糖和α-氨基异丁酸的温度敏感性摄取监测，诱导了内吞作用、己糖转运和氨基酸转运的早期（不到30 - 60秒）刺激。这种刺激具有时间和浓度依赖性，在10^(-9)至10^(-8) M睾酮时达到最大值，这与雄激素受体介导一致。EGTA（2.5 mM）、La3+（1 mM）和维拉帕米（100 μM）消除了激素反应。钙离子载体A23187（10 μM）诱导了内吞作用、氨基酸转运和己糖转运的急性刺激，睾酮（10^(-8) M）并未使其进一步增加，提示存在共同的效应途径。睾酮（10^(-8) M）还引起了45Ca内流和外流的快速（不到30秒）刺激。睾酮（10^(-8) M）在分离的心肌细胞中诱导了鸟氨酸脱羧酶（ODC）活性的快速（不到5秒）短暂增加，在60秒时达到峰值（两倍至三倍），以及多胺的早期（15秒）短暂积累，在60秒时达到峰值。特异性、不可逆的ODC抑制剂α-二氟甲基鸟氨酸（DFMO，5 - 10 mM）阻断了睾酮诱导的ODC活性和多胺水平的增加以及Ca2+通量、内吞作用、己糖转运和氨基酸转运的刺激。ODC产物腐胺（0.5 - 1 mM）逆转了DFMO的抑制作用，并恢复了多胺、45Ca通量和Ca2+依赖性膜转运过程的增加。这些结果表明，快速、短暂的ODC调节的多胺合成对于雄激素刺激心室肌细胞中的Ca2+通量和膜转运过程至关重要。这些发现支持了一种信号转导模型，其中新合成的多胺作为细胞内信使来调节跨膜Ca2+运动、Ca2+依赖性膜转运功能以及心肌细胞中其他Ca2+和多胺敏感的过程。
