Urine Hormones Modulate Sodium Metabolism

Abnormal sodium metabolism may be critical in the causation of certain forms of hypertension, particularly salt-sensitive hypertension. In a recent study, two closely related small molecules isolated from human urine have been found to modulate sodium excrement without causing concurrent removal of potassium.

Investigators from Harvard Medical School (Boston, MA, USA) used an innovative technique to analyze partially purified urine samples enriched in natriuretic activity by nuclear magnetic resonance (NMR) spectroscopy. They reported in the November 6, 2007, issue of the Proceedings of the [U.S.] National Academy of Sciences (PNAS) that they had the isolated and identified two small molecules, xanthurenic acid 8-O-beta-D-glucoside and xanthurenic acid 8-O-sulfate. Both compounds caused substantial and sustained (one to two-hour) natriuresis in rats with no or minimal concomitant potassium excretion.

The newly discovered molecules are structurally similar to such amino acid-derived neurotransmitters as dopamine and serotonin, and therefore, may also play other roles in the body. "Now, we want to know what other functions these compounds have and whether they directly influence blood pressure,” said senior author Dr. Frank Schroeder, professor of biological chemistry and molecular pharmacology at Harvard Medical School.


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