Dietary salt with nitric oxide deficiency induces nocturnal polyuria in mice via hyperactivation of intrarenal angiotensin II-SPAK-NCC pathway.

Nocturnal polyuria is the most frequent cause of nocturia, a common disease associated with a compromised quality of life and increased mortality. Its pathogenesis is complex, and the detailed underlying mechanism remains unknown. Herein, we report that concomitant intake of a high-salt diet and reduced nitric oxide (NO) production achieved through Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME) administration in mice resulted in nocturnal polyuria recapitulating the clinical features in humans. High salt intake under reduced NO production overactivated the angiotensin II-SPAK (STE20/SPS1-related proline-alanine-rich protein kinase)-NCC (sodium chloride co-transporter) pathway in the kidney, resulting in the insufficient excretion of sodium during the day and its excessive excretion at night. Excessive Na excretion at night in turn leads to nocturnal polyuria due to osmotic diuresis. Our study identified a central role for the intrarenal angiotensin II-SPAK-NCC pathway in the pathophysiology of nocturnal polyuria, highlighting its potential as a promising therapeutic target.

Genetic characteristics of double hypoglossal canal as a nonmetric trait.

The hypothesis that the hypoglossal canal bridging or double (HGCD), a nonmetric cranial trait, is a powerful discriminator between populations (Dodo, 1980, 1987) is still controversial. To examine this issue, the incidences of HGCD were investigated in six inbred mice strains (CBA, C57BL, BALB/c, Strong A, NZB, and DAB) and one group of wild mice, six matings of CBA and C57BL, and four experimental diet groups. The above hypothesis was supported by some results such as no effects of diet on the incidences of HGCD and significant differences among the incidences of HGCD in some inbred strains. However, significant differences were also detected in the incidences of HGCD among groups within an inbred strain. Therefore, we think that further conservative and experimental assessments should be performed to determine the usefulness of incidences of HGCD as a powerful discriminator in skeletal studies on populations and family history.