Gellai M, Ruffolo R R
J Pharmacol Exp Ther. 1987 Mar;240(3):723-8.
The effects of the selective alpha-1 adrenoceptor agonist, cirazoline, and the selective alpha-2 adrenoceptor agonist, B-HT 933, were assessed on renal hemodynamics and on water and solute excretion in conscious, chronically instrumented rats. Infusion (i.v.) of equipressor doses of cirazoline and B-HT 933, 0.04 and 4 mg/kg/hr, respectively, decreased renal plasma flow without changing glomerular filtration rate. Cirazoline infusion did not affect urinary excretion of water, electrolytes or total solutes. In marked contrast, B-HT 933 increased urine flow and sodium excretion significantly (P less than .01) but did not significantly alter potassium and urea excretion. Urine osmolality decreased to hyposmotic levels (from 613 +/- 86 to 172 +/- 8 mOsmol/kg of H2O) during the infusion of B-HT 933, suggesting a possible interaction between the alpha-2 adrenoceptor agonist and the vasopressin system. This diuretic action of the selective alpha-2 adrenoceptor agonist was also observed after the i.v. infusion of a subpressor dose (0.4 mg/kg/hr) of B-HT 933. In rats treated with the ganglionic blocker, hexamethonium (10 mg/kg i.v.), the B-HT 933-induced diuresis was not affected, confirming an action in the periphery, possibly at the level of the kidney. These results suggest that stimulation of renal alpha-2 adrenoceptors in conscious, euvolumic rats modulates the reabsorption of water and sodium at the site of the renal nephron.
在清醒、长期植入仪器的大鼠中，评估了选择性α-1肾上腺素能受体激动剂西拉唑啉和选择性α-2肾上腺素能受体激动剂B-HT 933对肾血流动力学以及水和溶质排泄的影响。分别以0.04和4mg/kg/小时的等压剂量静脉输注西拉唑啉和B-HT 933，可降低肾血浆流量，而不改变肾小球滤过率。输注西拉唑啉不影响水、电解质或总溶质的尿排泄。与之形成显著对比的是，B-HT 933显著增加尿流量和钠排泄（P<0.01），但对钾和尿素排泄无显著影响。在输注B-HT 933期间，尿渗透压降至低渗水平（从613±86降至172±8mOsmol/kg H2O），提示α-2肾上腺素能受体激动剂与血管加压素系统之间可能存在相互作用。在静脉输注亚升压剂量（0.4mg/kg/小时）的B-HT 933后，也观察到了选择性α-2肾上腺素能受体激动剂的这种利尿作用。在用神经节阻滞剂六甲铵（10mg/kg静脉注射）治疗的大鼠中，B-HT 933诱导的利尿作用未受影响，证实其在外周起作用，可能在肾脏水平。这些结果表明，刺激清醒、血容量正常大鼠的肾α-2肾上腺素能受体会调节肾单位部位水和钠的重吸收。
