Department of Physiology and Biophysics, Instituto de Ciências Biomédicas, University of São Paulo, Av. Prof. Lineu Prestes, 1524, Cidade Universitária, 05508-900 SP, Brazil.
J Steroid Biochem Mol Biol. 2012 Feb;128(3-5):89-97. doi: 10.1016/j.jsbmb.2011.11.011. Epub 2011 Nov 30.
The rapid (2 min) nongenomic effects of aldosterone (ALDO) and/or spironolactone (MR antagonist), RU 486 (GR antagonist), atrial natriuretic peptide (ANP) and dimethyl-BAPTA (BAPTA) on the intracellular pH recovery rate (pHirr) via NHE1 (basolateral Na⁺/H⁺ exchanger isoform), after the acid load induced by NH₄Cl, and on the cytosolic free calcium concentration (Ca²⁺) were investigated in the proximal S3 segment isolated from rats, by the probes BCECF-AM and FLUO-4-AM, respectively. The basal pHi was 7.15±0.008 and the basal pHirr was 0.195±0.012 pH units/min (number of tubules/number of tubular areas=16/96). Our results confirmed the rapid biphasic effect of ALDO on NHE1: ALDO (10⁻¹² M) increases the pHirr to approximately 59% of control value, and ALDO (10⁻⁶ M) decreases it to approximately 49%. Spironolactone did not change these effects, but RU 486 inhibited the stimulatory effect and maintained the inhibitory effect. ANP (10⁻⁶ M) or BAPTA (5×10⁻⁵ M) alone had no significant effect on NHE1 but prevented both effects of ALDO on this exchanger. The basal Ca²⁺ was 104±3 nM (15), and ALDO (10⁻¹² or 10⁻⁶ M) increased the basal Ca²⁺ to approximately 50% or 124%, respectively. RU 486, ANP and BAPTA decreased the Ca²⁺ and inhibited the stimulatory effect of both doses of ALDO. The results suggest the involvement of GR on the nongenomic effects of ALDO and indicate a pHirr-regulating role for Ca²⁺ that is mediated by NHE1, stimulated/impaired by ALDO, and affected by ANP or BAPTA with ALDO. The observed nongenomic hormonal interaction in the S3 segment may represent a rapid and physiologically relevant regulatory mechanism in the intact animal under conditions of volume alterations.
用探针 BCECF-AM 和 FLUO-4-AM 分别研究了醛固酮（ALDO）和/或螺内酯（MR 拮抗剂）、RU 486（GR 拮抗剂）、心钠肽（ANP）和二甲氧基-BAPTA（BAPTA）对氯化铵诱导的酸负荷后通过基底外侧 Na⁺/H⁺交换体同工型 NHE1 的细胞内 pH 恢复率（pHirr）以及细胞浆游离钙浓度 (Ca²⁺) 的快速（2 分钟）非基因组效应。从大鼠分离的近端 S3 段，基础 pHi 为 7.15±0.008，基础 pHirr 为 0.195±0.012 pH 单位/分钟（肾小管数/管状面积数=16/96）。我们的结果证实了 ALDO 对 NHE1 的快速双相作用：ALDO（10⁻¹² M）将 pHirr 增加到对照值的约 59%，而 ALDO（10⁻⁶ M）将其降低到约 49%。螺内酯不改变这些作用，但 RU 486 抑制了刺激作用并维持了抑制作用。ANP（10⁻⁶ M）或 BAPTA（5×10⁻⁵ M）单独对 NHE1 没有显著影响，但可防止 ALDO 对该交换器的两种作用。基础 Ca²⁺ 为 104±3 nM（15），ALDO（10⁻¹² 或 10⁻⁶ M）分别将基础 Ca²⁺ 增加到约 50%或 124%。RU 486、ANP 和 BAPTA 降低 Ca²⁺ 并抑制两种剂量的 ALDO 的刺激作用。结果表明，GR 参与了 ALDO 的非基因组作用，并表明 Ca²⁺ 对 pHirr 具有调节作用，该作用通过 NHE1 介导，受 ALDO 刺激/受损，并受 ALDO 下的 ANP 或 BAPTA 影响。在体积改变条件下，在完整动物中，S3 段观察到的非基因组激素相互作用可能代表一种快速且与生理相关的调节机制。
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