Chen L, Reif M C, Schafer J A
Department of Physiology, University of Alabama, Birmingham 35294.
Am J Physiol. 1991 Jul;261(1 Pt 2):F126-36. doi: 10.1152/ajprenal.1991.261.1.F126.
We examined the effects of prostaglandin E2 (PGE2) and the adrenergic agonist clonidine on osmotic water permeability (Pf), lumen-to-bath 22Na+ flux (Jl----b), and transepithelial voltage (VT) in isolated perfused cortical collecting ducts (CCD) from rats and rabbits. Although PGE2 inhibited arginine vasopressin (AVP)-dependent Jl----b and Pf in CCDs from deoxycorticosterone (DOC)-treated and untreated rabbits, 0.1-10 microM PGE2 had no inhibitory effect on any of these transport parameters in CCDs from DOC-treated rats in presence of AVP. On the other hand, clonidine (1 microM in bathing solution) reversibly inhibited AVP-dependent Pf, Jl----b, and VT in the rat CCD by 30-40%, and 0.3 microM yohimbine, a specific alpha 2-adrenoceptor antagonist, reversed these effects. However, we were unable to demonstrate any inhibitory effect of 1-10 microM clonidine on Pf, Jl----b, or VT in the rabbit CCD using a variety of protocols. These results are consistent with the pattern of inhibition of AVP-dependent adenosine 3',5'-cyclic monophosphate (cAMP) production in the rat and rabbit CCD in that PGE2 inhibits both transport and cAMP production in the rabbit but not the rat CCD, and clonidine inhibits both transport and cAMP production in the rat but not the rabbit CCD [D. Chabardès, C. Brick-Ghannam, M. Montégut, and S. Siaume-Perez, Am. J. Physiol. 255 (Renal Fluid Electrolyte Physiol. 24): F43-F48, 1988].
我们研究了前列腺素E2（PGE2）和肾上腺素能激动剂可乐定对大鼠和家兔离体灌注皮质集合管（CCD）的渗透水通透性（Pf）、管腔至浴液的22Na+通量（Jl----b）以及跨上皮电压（VT）的影响。尽管PGE2抑制了脱氧皮质酮（DOC）处理和未处理家兔的CCD中精氨酸加压素（AVP）依赖性的Jl----b和Pf，但在存在AVP的情况下，0.1 - 10微摩尔/升的PGE2对DOC处理大鼠的CCD中的任何这些转运参数均无抑制作用。另一方面，可乐定（浴液中1微摩尔/升）可逆性地抑制大鼠CCD中AVP依赖性的Pf、Jl----b和VT达30 - 40%，而0.3微摩尔/升的育亨宾（一种特异性α2 - 肾上腺素能受体拮抗剂）可逆转这些作用。然而，我们使用多种实验方案未能证明1 - 10微摩尔/升可乐定对家兔CCD中的Pf、Jl----b或VT有任何抑制作用。这些结果与大鼠和家兔CCD中AVP依赖性的3',5'-环磷酸腺苷（cAMP）生成的抑制模式一致，即PGE2抑制家兔而非大鼠CCD中的转运和cAMP生成，可乐定抑制大鼠而非家兔CCD中的转运和cAMP生成[D. 沙巴尔德、C. 布里克 - 加南姆、M. 蒙特居和S. 西亚姆 - 佩雷斯，《美国生理学杂志》255（肾脏液体电解质生理学24）：F43 - F48，1988]。
