Exaggerated natriuresis as a candidate intermediate phenotype in spontaneously hypertensive rats

81 backcross rats (developed by mating borderline hypertensive rats with Wistar-Kyoto rats) fed 8% NaCl food for 12 weeks from age 4 to 16 weeks, chronically instrumented for measurement of mean arterial pressure, renal sympathetic nerve activity, and urinary sodium excretion

Intravenous isotonic saline volume loading (10% body weight/30 min)

Correlation between mean arterial pressure and the magnitude of decrease in renal sympathetic nerve activity or increase in urinary sodium excretion during volume loadingsurrogate