Specht S C, Martin J, Gaud R E, De Hoyos J
Department of Pharmacology, University of Puerto Rico, San Juan.
Biochim Biophys Acta. 1991 Dec 11;1118(1):77-82. doi: 10.1016/0167-4838(91)90443-4.
Na+/K(+)-ATPase was evaluated in the retina and kidney of the spontaneously diabetic BB/Wor rat after 1 and 4 months of insulin dependency. Retinal synthesis of the Na+/K(+)-ATPase was measured during a 2-h intravitreal pulse of [35S]methionine and analyzed by SDS-PAGE and scintillation counting. Synthesis of the alpha-1 and 'alpha(+)' (includes both alpha-2 and alpha-3) isoforms of the catalytic subunit was increased 123% and 69%, respectively at 4 months. Increases were also suggested at 1 month, but were not significant. The diabetes-dependent peak of synthesis in long-term diabetic rats turned over rapidly and by 3 days after intravitreal labeling, radioactively labeled enzyme was equal in both control and diabetic retinae. The amount of axonally transported, labeled enzyme recovered from endings of the optic nerve in the superior colliculus paralleled retinal labeling. Significant renal hypertrophy (48%) was noted at 4 months, but not at 1 month. The strophanthidin-inhibition constant for diabetes-induced renal enzyme was the same as for control enzyme (approx. 10(-4) M), indicating that diabetic renal hypertrophy does not induce a Na pump isozyme that is more sensitive to cardiotonic steroids. SDS-PAGE of the renal enzyme also failed to indicate more than one isoform of the alpha subunit.
在胰岛素依赖1个月和4个月后，对自发性糖尿病BB/Wor大鼠的视网膜和肾脏中的钠钾ATP酶（Na+/K(+)-ATPase）进行了评估。在2小时的玻璃体内[35S]蛋氨酸脉冲期间测量视网膜中钠钾ATP酶的合成，并通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）和闪烁计数进行分析。在4个月时，催化亚基的α-1和“α(+)”（包括α-2和α-3）同工型的合成分别增加了123%和69%。在1个月时也有增加的趋势，但不显著。长期糖尿病大鼠中依赖糖尿病的合成峰值周转迅速，在玻璃体内标记后3天，放射性标记的酶在对照视网膜和糖尿病视网膜中相等。从上丘的视神经末梢回收的轴突运输的标记酶的量与视网膜标记平行。在4个月时观察到显著的肾脏肥大（48%），但在1个月时未观察到。糖尿病诱导的肾脏酶的毒毛花苷抑制常数与对照酶相同（约10(-4) M），这表明糖尿病性肾脏肥大不会诱导对强心苷更敏感的钠泵同工酶。肾脏酶的SDS-PAGE也未能显示α亚基有不止一种同工型。
