Rasio E A, Bendayan M, Goresky C A
Department of Medicine, Hôpital Notre-Dame, Montreal, Quebec, Canada.
Circ Res. 1995 Apr;76(4):566-74. doi: 10.1161/01.res.76.4.566.
The effects of second-messenger concentration changes on capillary diffusion capacity (permeability-surface area product [PS]) to cellular and paracellular tracers and on capillary ultrastructure were studied during countercurrent perfusion of the rete of the eel swim bladder. Cyclic nucleotide effects were investigated with isoproterenol, forskolin, and dibutyryl cAMP. Isoproterenol (5 x 10(-6) mol/L) did not modify water and solute permeability or capillary structure. Forskolin (10(-4) mol/L) immediately raised the concentrations of cAMP in the rete and produced interstitial edema but did not change permeability. The addition of dibutyryl cAMP (10(-6) mol/L) to the perfusate had rapid effects: it reduced the PS of [3H]water and oxygen and increased the PS of [125I]albumin, [14C]sucrose, and 22Na. No structural changes were observed. Phosphoinositide effects were studied with 1,2-dioctanoyl-sn-glycerol (DG) and phorbol 12-myristate 13-acetate (PMA). DG (10(-5) mol/L) had no effect on the permeability of the rete to water and solutes, while inducing cell membrane vacuolization. PMA (10(-5) mol/L) progressively reduced the PS of [3H]water. In contrast, PS values of [125I]albumin, [14C]sucrose, and 22Na rose gradually. Membrane vacuoles bulging into the lumen and in the cytoplasm were a common feature. The Ca2+ effect was investigated with the Ca2+ ionophore A23187. At 5 x 10(-6) mol/L, unsteady permeability changes and extensive cytolysis were observed. At 5 x 10(-7) mol/L, the PS of [125I]albumin, [14C]sucrose, and 22Na rapidly increased. The PS values for water were not modified. No structural changes were identified.(ABSTRACT TRUNCATED AT 250 WORDS)
在对鳗鱼鳔网进行逆流灌注期间，研究了第二信使浓度变化对毛细血管对细胞内和细胞旁示踪剂的扩散能力（通透表面积乘积[PS]）以及对毛细血管超微结构的影响。用异丙肾上腺素、福斯高林和二丁酰环磷酸腺苷研究了环核苷酸的作用。异丙肾上腺素（5×10⁻⁶mol/L）未改变水和溶质的通透性或毛细血管结构。福斯高林（10⁻⁴mol/L）立即提高了鳔网中环磷酸腺苷的浓度并导致间质水肿，但未改变通透性。向灌注液中添加二丁酰环磷酸腺苷（10⁻⁶mol/L）产生了快速效应：它降低了[³H]水和氧气的PS，并增加了[¹²⁵I]白蛋白、[¹⁴C]蔗糖和²²Na的PS。未观察到结构变化。用1,2 - 二辛酰 - sn - 甘油（DG）和佛波醇12 - 肉豆蔻酸酯13 - 乙酸酯（PMA）研究了磷酸肌醇的作用。DG（10⁻⁵mol/L）对鳔网对水和溶质的通透性没有影响，同时诱导细胞膜空泡化。PMA（10⁻⁵mol/L）逐渐降低了[³H]水的PS。相反，[¹²⁵I]白蛋白、[¹⁴C]蔗糖和²²Na的PS值逐渐升高。膜空泡向管腔和细胞质中突出是一个常见特征。用钙离子载体A23187研究了Ca²⁺的作用。在5×10⁻⁶mol/L时，观察到不稳定的通透性变化和广泛的细胞溶解。在5×10⁻⁷mol/L时，[¹²⁵I]白蛋白、[¹⁴C]蔗糖和²²Na的PS迅速增加。水的PS值未改变。未发现结构变化。（摘要截断于250字）
