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KMID : 0438219770140010117
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Korea University Medical Journal
1977 Volume.14 No. 1 p.117 ~ p.124
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Effect of alpha-Adrenergic Agent on Water Diuresis
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黃彩奎/Hwang, Chai Kyu
洪淳國/Hong, Soon Kuk
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Abstract
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Norepinephrine increases urine flow rate and free water clearance without altering glomerular filtration rate and without or moderately reducing renal plasma flow in man and animal. This effect was most apparent when the control values of free water clearance were negative, norepinephrine exerted this effect by decreasing tubular water reabsorption. It was reported that nor-epinephrine inhibit the in vitro action of vasopressin on water transport by the toad bladder suggested that the in vivo effect of norepinephrine on water excretion might be mediated by a similar mechanism.
On the other hand it was well documented that norepinephrine, the principal endogenous alphaadrenergic agent, produces constriction of renal arteries and vasa recta. It was also noted that increased renal arterial perfusion pressure produce pressure diuresis, while constriction of vasa recta reserve the osmotic gradient of medulla and renal concentrating ability.
The present experiments were performed to examine the effect of norepinephrine on renal tubular function to determine if these effects are related to changes in renal hemodynamics.
On experiments 20 rabbits were infused with 2.5% dextrose solution until water diuresis were maintained and thereafter simultaneous administration of pitressin (20pU/kg/min), and then pitressin (20pU/kg/min) plus noradrenalin (0.5gg/kg/min) were performed. During experiments urine volume, Cl., Cosm, CHZO, sodium excretion and CpAII, Epgg, RPF, FF, NCPF were measured for four consecutive specimens every twenty minutes intervals respectively.
The results were as follows:
1) Total renal plasma flow, cortical plasma flow, filtration fraction and medullary plasma flow were not altered by administration of water, pitressin and noradrenalin.
2) Water diutesis was inhibited by pitressin, while pitressin induced antidiutesis was irlfiibited by noradrenalin.
!i 3) Glom--rular filtrltioa rate-, L)sm)lar cleara!tc-, and solium excretion were not altered by pitressin and noradrenalin.
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