Further evidence for a humoral natriuretic factor.

Abstract

This chapter provides biochemical evidences for a humoral natriuretic factor. The regulation of salt excretion is among the most important determinants that modifies the concentration of sodium in the extracellular fluid and, hence, its osmolality and that of the intracellular fluid; modifies the distribution of fluid between the major compartments; modifies the volume of the extracellular phase; and perhaps most significant of all, in turn, plays a vital role in the circulation of the blood and all the conditions attendant on this remarkable phenomenon. It is possible that the increased sodium excretion in the donor dogs might have been due to factors other than a humoral natriuretic substance. Thus, it seems quite clear that a highly significant natriuresis obtains in a nonexpanded dog when this particular cross circulation technique is employed. It is also possible that a natriuretic factor is elaborated but its effect on the kidney might not be seen in the absence of dilution of the extravascular fluid.