Breen C M, Mannon P J, Benjamin B A
Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.
Am J Physiol. 1998 Sep;275(3):F452-7. doi: 10.1152/ajprenal.1998.275.3.F452.
mIMCD-k2 cells are derived from the inner medullary collecting duct of a mouse and exhibit electrogenic sodium absorption and cAMP- and vasopressin (AVP)-stimulated electrogenic chloride secretion [N. L. Kizer, B. Lewis, and B. A. Stanton. Am. J. Physiol. 268 (Renal Fluid Electrolyte Physiol. 37): F347-F355, 1995; and N. L. Kizer, D. Vandorpe, B. Lewis, B. Bunting, J. Russell, and B. A. Stanton. Am. J. Physiol. 268 (Renal Fluid Electrolyte Physiol. 37): F854-F861, 1995]. The purpose of the present study was to determine how peptide YY (PYY) affects electrogenic Na+ and Cl- current in mIMCD-k2 cells. Short-circuit currents (Isc) were measured across monolayers of mIMCD-k2 cells mounted in Ussing-type chambers. PYY did not alter baseline Isc, nor did it alter Isc in chloride-free conditions, indicating no effect on electrogenic sodium transport. Baseline chloride current in these cells is low; therefore, chloride short-circuit current (IClsc) was stimulated with AVP (10 nM) added to the basolateral surface and 10 microM amiloride added to the apical surface. Although apical applications of PYY had no effect, basolateral application of PYY caused attenuation of IClsc, with the maximal inhibitory dose (100 nM) causing 52 +/- 1.3% inhibition (IC50 = 0.11 nM). Inhibition by PYY of IClsc is mediated through the Y2 receptor subtype, as PYY-(3-36) was the only PYY analog tested that caused inhibition and was equipotent to PYY. Inhibition by PYY of IClsc was abolished following incubation with pertussis toxin. We also show that PYY inhibits AVP-stimulated cAMP accumulation, with a maximal inhibitory dose (100 nM) causing a 38% +/- 6% inhibition (IC50 = 0.16 nM), comparable to inhibition by PYY of IClsc. We conclude that PYY acts through either Gi or Go to inhibit adenylate cyclase activity, leading to a decrease in AVP-stimulated chloride current.
mIMCD - k2细胞源自小鼠的髓质内集合管，表现出电中性钠吸收以及环磷酸腺苷（cAMP）和血管加压素（AVP）刺激的电中性氯分泌[N. L. 凯泽、B. 刘易斯和B. A. 斯坦顿。《美国生理学杂志》268卷（肾流体电解质生理学37）：F347 - F355，1995年；以及N. L. 凯泽、D. 万多普、B. 刘易斯、B. 邦廷、J. 拉塞尔和B. A. 斯坦顿。《美国生理学杂志》268卷（肾流体电解质生理学37）：F854 - F861，1995年]。本研究的目的是确定肽YY（PYY）如何影响mIMCD - k2细胞中的电中性Na⁺和Cl⁻电流。通过安装在尤斯灌流室中的mIMCD - k2细胞单层测量短路电流（Isc）。PYY不改变基线Isc，在无氯条件下也不改变Isc，表明对电中性钠转运无影响。这些细胞中的基线氯电流较低；因此，在基底外侧表面添加AVP（10 nM）并在顶端表面添加10 μM氨氯吡脒来刺激氯短路电流（IClsc）。尽管顶端应用PYY没有作用，但基底外侧应用PYY导致IClsc衰减，最大抑制剂量（100 nM）引起52±1.3%的抑制（IC50 = 0.11 nM）。PYY对IClsc的抑制是通过Y2受体亚型介导的，因为PYY -（3 - 36）是所测试的唯一引起抑制且与PYY等效的PYY类似物。用百日咳毒素孵育后，PYY对IClsc的抑制作用被消除。我们还表明，PYY抑制AVP刺激的cAMP积累，最大抑制剂量（100 nM）引起38%±6%的抑制（IC50 = 0.16 nM），与PYY对IClsc的抑制作用相当。我们得出结论，PYY通过Gi或Go起作用以抑制腺苷酸环化酶活性，导致AVP刺激的氯电流降低。
