Michell A R, White D G, Higgins A J, Moss P, Lees P
Res Vet Sci. 1986 Mar;40(2):264-70.
The hypothesis that the toxic effects of imidocarb mediated by reduced cholinesterase activity might be intensified by hypomagnesaemia was tested in calves. Hypomagnesaemia was induced in 12 males (50 kg) using an artificial milk based on a commercial nondairy coffee creamer. Although plasma magnesium levels reached 0.33 mmol litre-1 in two weeks no clinical signs were detected. In 12 control calves a daily magnesium supplement of 0.6 g was inadequate although the published requirement is 0.45 g; it was raised to 1.2 g to keep plasma magnesium normal. Lighter calves developed hypomagnesaemia more readily and fast-growing calves had lower plasma urea concentrations. Plasma calcium, but not plasma magnesium, showed significant positive correlation with plasma albumin. The only statistically significant effects of hypomagnesaemia were slight elevations of white cell count and plasma sodium. The hypomagnesaemic and normomagnesaemic calves were divided into two equal groups and treated with 3.3 mg kg-1 of imidocarb dipropionate or a placebo. The drug produced the expected clinical signs of mild toxicity and depression of cholinesterase but no other adverse effects. Transient slight depressions of plasma calcium and potassium concentration, a transient rise of plasma sodium and elevation of creatine kinase occurred. None of the effects of imidocarb treatment was intensified by hypomagnesaemia except, perhaps, constriction of the pupils; generally, hypomagnesaemic animals were affected less.
在犊牛身上检验了低镁血症可能会加剧因胆碱酯酶活性降低介导的咪唑苯脲毒性作用这一假说。使用基于市售非乳制咖啡奶精的人工乳，在12头雄性犊牛（50千克）中诱导产生低镁血症。尽管两周内血浆镁水平达到了0.33毫摩尔/升，但未检测到临床症状。在12头对照犊牛中，每日补充0.6克镁并不充足，尽管已公布的需求量为0.45克；将其提高到1.2克以维持血浆镁正常。较轻的犊牛更容易出现低镁血症，生长快速的犊牛血浆尿素浓度较低。血浆钙而非血浆镁与血浆白蛋白呈显著正相关。低镁血症唯一具有统计学意义的影响是白细胞计数和血浆钠略有升高。将低镁血症和正常镁血症的犊牛分为两组，每组数量相等，分别用3.3毫克/千克的双丙酸咪唑苯脲或安慰剂进行治疗。该药物产生了预期的轻度毒性临床症状和胆碱酯酶抑制，但未产生其他不良反应。出现了血浆钙和钾浓度的短暂轻微降低、血浆钠的短暂升高以及肌酸激酶升高。除了可能的瞳孔收缩外，低镁血症并未加剧咪唑苯脲治疗的任何影响；总体而言，低镁血症动物受到的影响较小。
