钾缺乏时的血管加压素抵抗：钠钾泵的作用

Vasopressin resistance in potassium depletion: role of Na-K pump.

作者信息

Mujais S K, Chen Y, Nora N A

机构信息

Department of Medicine, Northwestern University Medical School, Chicago, Illinois.

出版信息

Am J Physiol. 1992 Oct;263(4 Pt 2):F705-10. doi: 10.1152/ajprenal.1992.263.4.F705.

DOI:10.1152/ajprenal.1992.263.4.F705

PMID:1329558

Abstract

Resistance to the hydrosmotic effects of vasopressin has been described in K depletion. It is not clear whether other effects of vasopressin, notably its effects on the Na-K pump in the collecting duct, are similarly affected. Adrenalectomized male Sprague-Dawley rats were allocated to either a normal K (NK) or low-K (LK) diet. Na-K pump activity (pmol.mm-1.h-1) in cortical collecting duct (CCD) and medullary collecting duct (MCD) was determined at 21 days after allocation to the dietary groups before and after exogenous vasopressin (0.1 U twice daily for 3 days). In animals on NK diet, vasopressin (AVP) led to a doubling of Na-K pump activity in the CCD from 502 +/- 47 to 1,144 +/- 41 pmol.mm-1.h-1 (P < 0.01). In K-depleted animals, which had a higher baseline Na-K pump activity, an increase was also observed from 1,056 +/- 97 to 1,239 +/- 65 pmol.mm-1.h-1 (P < 0.05), but this increase was quantitatively less, with the change being 183 vs. 642 pmol.mm-1.h-1 in K-replete rats. The findings in the MCD were similar; in rats on a NK diet, AVP led to a significant increase in Na-K pump activity from 498 +/- 29 to 830 +/- 28 pmol.mm-1.h-1 (P < 0.01). With K depletion, this directional change was preserved, increasing from 1,380 +/- 49 to 1,556 +/- 45 pmol.mm-1.h-1 (P < 0.05), but was quantitatively less than in K-replete rats, the change being 176 vs. 332 pmol.mm-1.h-1.(ABSTRACT TRUNCATED AT 250 WORDS)

摘要

钾缺乏时已发现对血管加压素的水渗透性作用存在抵抗。尚不清楚血管加压素的其他作用，尤其是其对集合管中钠钾泵的作用是否也受到类似影响。将肾上腺切除的雄性斯普拉格 - 道利大鼠分为正常钾（NK）饮食或低钾（LK）饮食组。在分配至饮食组21天后，于给予外源性血管加压素（每日两次，每次0.1 U，共3天）前后，测定皮质集合管（CCD）和髓质集合管（MCD）中的钠钾泵活性（pmol·mm⁻¹·h⁻¹）。在NK饮食的动物中，血管加压素（AVP）使CCD中的钠钾泵活性从502±47增加到1144±41 pmol·mm⁻¹·h⁻¹，增加了一倍（P<0.01）。在基线钠钾泵活性较高的低钾动物中，也观察到从1056±97增加到1239±65 pmol·mm⁻¹·h⁻¹（P<0.05），但这种增加在数量上较少，低钾大鼠的变化为183 pmol·mm⁻¹·h⁻¹，而钾充足大鼠为642 pmol·mm⁻¹·h⁻¹。MCD中的结果相似；在NK饮食的大鼠中，AVP使钠钾泵活性从498±29显著增加到830±28 pmol·mm⁻¹·h⁻¹（P<0.01）。低钾时，这种方向性变化得以保留，从1380±49增加到1556±45 pmol·mm⁻¹·h⁻¹（P<0.05），但在数量上低于钾充足的大鼠，变化分别为176 pmol·mm⁻¹·h⁻¹和332 pmol·mm⁻¹·h⁻¹。（摘要截断于250字）