1H NMR study of renal trimethylamine responses to dehydration and acute volume loading in man.
We have used volume-localized 1H NMR spectroscopy to detect and measure changes in medullary trimethylamines (TMAs) in the human kidney in vivo. Localized water-suppressed 1H spectra were collected from a volume of interest located within the renal medulla by using a stimulated echo-based localization scheme. The principal resonances in the medullary 1H spectrum were residual water (4.7 ppm), lipid (0.9-1.4 ppm), and TMAs (3.25 ppm). The TMA line width was 7-15 Hz before filtering, and the signal-to-noise ratio was 40:1. In four normal volunteers, 15 hr of dehydration led to a significant increase in urine osmolality and decrease in body weight and an increase in medullary TMAs. A subsequent water load [20 ml.(kg of body weight)-1] caused a transient water diuresis, a return to euvolemic body weight, and a significant reduction in medullary TMAs within 4 hr. These results suggest that TMAs may play an osmoregulatory role in the medulla of the normal human kidney.
Avison
M J
MJ
Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06510.
Rothman
D L
DL
Nixon
T W
TW
Long
W S
WS
Siegel
N J
NJ
D000328:Adult; D003681:Dehydration / Q000503:physiopathology*; D004326:Drinking; D006801:Humans; D006859:Hydrogen; D007668:Kidney / Q000502:physiology*; D007679:Kidney Medulla / Q000502:physiology; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D008744:Methylamines; D014867:Water
D008744:Methylamines; D014867:Water; D006859:Hydrogen; C023336:trimethylamine