Effect of sodium-ethylenediamine-tetraacetate on renal function.

Renal function was tested after decreasing the plasma ionized calcium level of renal artery. During EDTA infusion, renal blood flow (RBFdir) increased, while CPAH, Ccreat, EPAH and Ecreat decreased. In the left kidney, urinary and sodium excretion did not change significantly, while calcium excretion reached a fifteen-fold higher value than the control one. The unchanged urinary and sodium excretion in spite of the decreased glomerular filtration rate may have been due to the osmotic diuretic effect of the Ca-EDTA complex. The decrease of CPAH and EPAH was probably the consequence of a change in the secretory capacity in the absence of Ca++. the vasodilatation occurring in the efferent arterioles during EDTA infusion would serve to explain the decrease in the glomerular filtration rate. It is concluded that humoral vasoactive factors, mainly angiotensin, may have an important role in the regulation of the diameter of the efferent arterioles and in this way in the regulation of glomerular function.