Prelot M, Do T X, Giraul A, Thuillier A
Laboratoires de Physiologie, de Biochimie appliquée (CHU), de Pharmacie clinique, UFR des Sciences Médicales et de Pharmaceutiques, Angers, France.
Arch Int Physiol Biochim Biophys. 1991 Jun;99(3):269-73. doi: 10.3109/13813459109146934.
The effects of 24R,25-dihydroxyvitamin D3 (24,25-(OH)2D3 on alkaline phosphatase (PAL), gamma-glutamyltransferase (GGT) and acid phosphatase (PAC) activities were investigated on renal cortex slices of hypophysectomized rats. Indeed after hypophysectomy renal 24,25-(OH)2D3 production was increased and renal PAL and GGT activities were decreased. After 5h incubation with physiological concentrations (0.1-10 nM) of 24,25-(OH)2D3 significant increases of PAL and GGT activities were produced. The maximum stimulation obtained with 1 nM was +23% for PAL and +26% for GGT as compared to controls. PAC was not modified. The time course of these effects was studied from 45 min to 8 h. In the presence of 24,25-(OH)2D3 (1 nM), delayed (3h) stimulation of PAL and GGT appeared. It reached the maximal value after 6h, +37% for PAL and +30% for GGT and persisted again at 8h. Cycloheximide added to incubation medium with steroid inhibited the stimulating effect on PAL only. Actinomycin D suppressed the induction of both enzymes, indicating that the observed actions of 24,25-(OH)2D3 depend on protein synthesis whose responsible mechanisms were different. These protein synthesis inhibitors did not modified enzymatic activities. Physiological significance of these renal effects is to be clarified.
研究了24R,25-二羟基维生素D3（24,25-(OH)2D3）对垂体切除大鼠肾皮质切片中碱性磷酸酶（PAL）、γ-谷氨酰转移酶（GGT）和酸性磷酸酶（PAC）活性的影响。事实上，垂体切除后，肾脏24,25-(OH)2D3的生成增加，而肾脏PAL和GGT活性降低。用生理浓度（0.1 - 10 nM）的24,25-(OH)2D3孵育5小时后，PAL和GGT活性显著增加。与对照组相比，1 nM的24,25-(OH)2D3产生的最大刺激作用为PAL增加23%，GGT增加26%。PAC活性未改变。从45分钟到8小时研究了这些作用的时间进程。在存在24,25-(OH)2D3（1 nM）的情况下，PAL和GGT出现延迟（3小时）刺激。6小时后达到最大值，PAL为37%，GGT为30%，并在8小时时再次持续。添加到含类固醇孵育培养基中的放线菌酮仅抑制对PAL的刺激作用。放线菌素D抑制这两种酶的诱导，表明观察到的24,25-(OH)2D3的作用依赖于蛋白质合成，但其负责机制不同。这些蛋白质合成抑制剂未改变酶活性。这些肾脏作用的生理意义有待阐明。
