Role of the basal sodium intake in the rats on their response to a natriuretic factor

Abstract

A previously described natriuretic factor found in urine from man and dogs receiving a high salt diet has been postulated to be of hormonal nature. In order to test this hypothesis, natriuretic factor obtained from a pool of human urine of a standard activity has been injected into rats fed 0.55 (group A), 3.55 (group B), 6.55 (group C) mEq sodium a day as it has been shown that the endogenous activity of this factor depends on the sodium content of the diet. This material induces an increment of the UNaV and FENa in the rats averaging respectively 429.6 +/- 150.1% and 317.5 +/- 71.14% for the rats from group A, 103 +/- 29% and 99.7 +/- 26.25% for the rats from group B, 56.3 +/- 34.4% and 63.2 +/- 35.8% for the rats from group C reflecting the degree of statistical significance observed between the absolute values obtained during the control and experimental periods for each group. In addition, a dose-response curve has been established. Altogether the results suggest the hormonal nature of the natriuretic factor and design the kidney as the target organ. These data allow to define the best conditions under which the rats have to be in order to provide a valuable bioassay for this natriuretic material.

Role of Prostaglandins in the Production of Natriuretic Factor by the Isolated Rat Kidney

“…In the present study the administration of in creasing amounts of the large MW natriuret ic factor to isolated rat kidneys induced a similar dose-response curve. The circum stances of production of the two natriuretic factors show some similarities in that no natriuretic activity could be detected in ne phrotic patients [15,22], The release of both factors was related to oral as well as paren teral sodium intake of men or animals [14][15][16][24][25][26][27][28][29], With the exception of Clarkson et al [23] who found some activity in the urine of subjects submitted to salt deprivation, no natriuretic effect was ob served when material provided by subjects or animals on low salt diet was injected. However, the subjects of Clarkson et al [23] received a low salt diet for shorter periods than did those described by others.…”

“…The natriuretic activity has been shown to be dose-related by Favre et al [24] who demonstrated that intravenous injection of increasing amounts of the low MW natriu retic factor into nonanesthetized intact rats resulted in a sigmoid dose-response curve. In the present study the administration of in creasing amounts of the large MW natriuret ic factor to isolated rat kidneys induced a similar dose-response curve.…”