Saleh Nahed, Aoki Mica, Shimada Terumasa, Akiyoshi Hideo, Hassanin Amin, Ohashi Fumihito
Laboratory of Veterinary Surgery, Graduate School of Agriculture and Biological Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai-shi, Osaka 599-8531, Japan.
J Vet Med Sci. 2005 May;67(5):461-5. doi: 10.1292/jvms.67.461.
Renal effects of the selective alpha(2)-adrenoceptor agonist, medetomidine, were investigated in anesthetized dogs. Animals were administered medetomidine 20 and 40 microg/kg intravenously (IV) and 80 mug/kg intramuscularly (IM) or 1 ml of saline IV. Urine and blood samples were collected before and at 30, 60, 90 and 120 min following medetomidine injection. Mean arterial blood pressure (MABP), renal blood flow (RBF), glomerular filtration rate (GFR), urine volume (U(v)), urine osmolality (U(osm)), free water clearance (C(H2O)), fractional clearance of sodium (F(Na)), plasma osmolality (P(osm)), plasma glucose levels and plasma antidiuretic hormone (ADH) concentrations were measured. The results showed that IV administration of medetomidine initially increased MABP 5-15 min followed by long-lasting decrease. The initial hypertension was not observed after IM administration, which was accompanied by a more profound hypotensive effects. RBF, GFR, U(v), C(H2O) increased after IV injection and decreased after IM. Medetomidine increased FNa and Posm and decreased U(osm). Plasma glucose levels initially increased and subsequently decreased. Plasma ADH concentration was decreased by IV injection but increased by IM administration. Our data imply that: 1) IV administration of medetomidine at dose rates of 20 and 40 microg/kg results in profound diuresis up to 2 hr; 2) Suppression of ADH release from the CNS is one of the mechanisms of medetomidine-induced diuresis although it may not be the principal one.
在麻醉犬中研究了选择性α₂肾上腺素能受体激动剂美托咪定对肾脏的影响。给动物静脉注射（IV）20和40微克/千克美托咪定、肌肉注射（IM）80微克/千克美托咪定或静脉注射1毫升生理盐水。在注射美托咪定前以及注射后30、60、90和120分钟采集尿液和血液样本。测量平均动脉血压（MABP）、肾血流量（RBF）、肾小球滤过率（GFR）、尿量（U(v)）、尿渗透压（U(osm)）、自由水清除率（C(H₂O)）、钠分数清除率（F(Na)）、血浆渗透压（P(osm)）、血浆葡萄糖水平和血浆抗利尿激素（ADH）浓度。结果显示，静脉注射美托咪定最初在5 - 15分钟内使MABP升高，随后出现持续降低。肌肉注射后未观察到最初的高血压，而是伴有更显著的降压作用。静脉注射后RBF、GFR、U(v)、C(H₂O)升高，肌肉注射后降低。美托咪定使FNa和Posm升高，U(osm)降低。血浆葡萄糖水平最初升高，随后降低。静脉注射使血浆ADH浓度降低，但肌肉注射使其升高。我们的数据表明：1）以20和40微克/千克的剂量静脉注射美托咪定可导致长达2小时的显著利尿；2）抑制中枢神经系统释放ADH是美托咪定诱导利尿的机制之一，尽管可能不是主要机制。
