氨基酸对蟾蜍卵母细胞膜电位的影响及其作用机制

本文采用微电极细胞内记录方法观察了23种氨基酸处理后蟾蜍卵母细胞膜电位的变化。丙氨酸、亮氨酸和赖氨酸可致膜电位去极化和膜K~+通透性降低,而色氨酸可致膜电位超极化和膜K~+通透性增加。其他19个氨基酸未见对膜电位有何作用。丙氨酸、亮氨酸和赖氨酸于引起去极化同时,还使卵母细胞孕酮含量成倍增加和卵母细胞趋于成熟。这些作用可被1mmol/L 丁酰 cAMP(db-cAMP)或 50μmol/L 雌二醇完全阻断。另一方面,色氨酸能阻断孕酮(10μmol/L)所致的去极化,但对 db-cAMP 所致的超极化无作用。本文讨论了氨基酸和甾类激素对卵母细胞成熟的调节作用。

EFFECTS OF AMINO ACIDS ON THE MEMBRANE POTENTIAL OF TOAD OOCYTES AND THE UNDERLYING MECHANISM

Of the 23 amino acids tested for their effect on the membrane potential of incubated toad oocyte, alanine, leucine and lysine were found to cause a decrease of polarization (depolarization) and K+ permeability, while tryptophan causes an increase of potential (hyperpolarization) and K+ permeability. For the rest 19 amino acids, no membrane effects were observed. Accompanying the alanine, leucine and lysine caused depolarization, the oocyte progesterone content became doubled and the maturation process hastened. These effects could be completely blocked by 1 mmol/L dibutyryl cAMP (db-cAMP) or 50 mumol/L estradiol. Tryptophan on the other hand could block the progesterone (10 mumol/L) induced depolarization but had no effect on the db-cAMP induced hyperpolarization. The regulatory function of the amino acids and steroid hormones underlying oocyte maturation is discussed.