The effects of peritubular ions and transport inhibitors were studied on methacholine (MCH)-induced sweat secretion by the isolated, cannulated monkey palm sweat glands in vitro and on the transepithelial and basolateral membrane potential (p.d.). 2. Sweat secretory rate was a curvilinear function of peritubular Na+ and Cl- concentration. Among the anion substitutes only Br- was able to totally substitute for Cl-. Presence of HCO3- or H2PO4- in the bath was not essential. 3. Both bumetanide and furosemide inhibited sweat secretion in a dose-dependent manner with the median effective concentration (EC50) of 3 X 10(-6) and 3 X 10(-5) M, respectively. 4. Bumetanide (10(-4) M) had no significant effect on basolateral membrane p.d. but nearly abolished the transepithelial p.d. 5. Hydrochlorothiazide (HCTZ, 3 X 10(-4) M) inhibited sweat secretion by only 35%. Inhibitors of ion exchangers amiloride (10(-4) M) and DIDS (4,4'-diisothiocyanostilbene-2,2'-disulphonic acid, 10(-4) M) lowered sweat secretion by less than 20%. 6. Removal of peritubular K+ as well as addition of 5 mM-Ba2+ also inhibited sweat rate. 5 mM-Ba2+ abolished the transepithelial p.d. and depolarized the basolateral p.d. by 26 mV, although the effects of Ba2+ on sweating and the transepithelial p.d. were only transient. 7. The data raise a possibility that either the NaCl or Na+-K+-2Cl- co-transport system or both may be involved in MCH-induced sweat secretion, whereas the role of parallel ion exchangers, if any, may be rather minor.
摘要
研究了肾小管周离子和转运抑制剂对离体插管猴掌汗腺在体外由乙酰甲胆碱（MCH）诱导的汗液分泌以及对跨上皮和基底外侧膜电位（p.d.）的影响。2. 汗液分泌速率是肾小管周Na⁺和Cl⁻浓度的曲线函数。在阴离子替代物中，只有Br⁻能够完全替代Cl⁻。浴液中HCO₃⁻或H₂PO₄⁻的存在并非必需。3. 布美他尼和呋塞米均以剂量依赖方式抑制汗液分泌，中位有效浓度（EC50）分别为3×10⁻⁶和3×10⁻⁵ M。4. 布美他尼（10⁻⁴ M）对基底外侧膜p.d.无显著影响，但几乎消除了跨上皮p.d.。5. 氢氯噻嗪（HCTZ，3×10⁻⁴ M）仅抑制汗液分泌35%。离子交换抑制剂氨氯地平（10⁻⁴ M）和4,4'-二异硫氰酸芪-2,2'-二磺酸（DIDS，10⁻⁴ M）使汗液分泌降低不到20%。6. 去除肾小管周K⁺以及添加5 mM Ba²⁺也抑制汗液分泌速率。5 mM Ba²⁺消除了跨上皮p.d.并使基底外侧p.d.去极化26 mV，尽管Ba²⁺对出汗和跨上皮p.d.的影响只是短暂的。7. 这些数据提示，NaCl或Na⁺-K⁺-2Cl⁻共转运系统或两者可能都参与了MCH诱导的汗液分泌，而平行离子交换器（如果有的话）的作用可能相当小。
