摘要:

AbstractA combination of31P and23Na NMR spectroscopy has been used to quantify the concentration of intracellular sodium, [Na]ICin the isolated and perfused mouse liver. The31P resonances of dimethyl methylphosphonate and LaDOTP5−, markers of total tissue space and extracellular space, respectively, were used to determine the intracellular liver volume. For a mean wet weight of 1.7 ± 0.3 g, the intracellular liver volume as measured by31P NMR averaged 1.2 ± 0.2 ml. The amount of intracellular sodium was measured from the baseline‐resolved intracellular23Na resonance during perfusion of the shift reagent, TmDOTP5−. These two measurements resulted in an NMR‐determined value for [Na]ICof 29.0 ± 5.2mM.Separate measurement of total tissue Tm and Na by atomic absorption spectroscopy on the same samples provided an AAS‐determined value for [Na]Icof 32.1 ± 7.4mM. These results indicate that intracellular sodium in the isolated, perfused liver is 100% visible by23Na NMR

ISSN:0740-3194    

DOI:10.1002/mrm.1910390122

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1998

数据来源: WILEY

摘要:

AbstractTo understand whether the NO‐dependent vasodilator L‐arginine was effective upon a chronically hypertensive cerebral capillary endothelium, dynamic susceptibility contrast MRI was used to measure the relative cerebral blood volume (rCBV) changes in nonischemic spontaneously hypertensive rats (SHRs). rCBV was measured in 11 rats at 4.7 T using fast gradient echo imaging with intravenous injection of Gd‐DTPA. Images were acquired before, immediately after, and up to 90 min after the infusion of 300 mg/kg L‐arginine (n= 7) or of an equivalent volume of saline (n= 4). L‐arginine increased rCBV in cortex beginning 10 min after infusion and reached significance after 30 min (P<0.01), reached a peak of 1.24 ± 0.06 (mean ± SEM) times pre‐injection level after 50 min, and was sustained throughout the 90 min observation period. In contrast, the rCBV in the deeper gray matter (striatum) showed no statistically significant change over the 90 min observation period. While this is consistent with previous studies showing that L‐arginine infusion can directly modulate vascular tone and cerebral hemodynamics, it demonstrates that the effect is present only in cortex, and that it can occur also in the setting of a disturbed capill

ISSN:0740-3194    

DOI:10.1002/mrm.1910390123

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1998

数据来源: WILEY

摘要:

AbstractThe construction of two novel mult‐segment (MS) resonators are described. The signal‐to‐noise ratio (SNR) and B1homogeneity of the coils are compared with that of a surface coil and a standard quadrature head coil. The images obtained with the MS designs revealed a surface coil‐like fall‐off in signal with depth. The SNR offered by MS coils was found to be better than the head coil at depths less than approximately 6 cm. Bilateral motor cortex activation on normal subjects performing finger tapping tasks is dem

ISSN:0740-3194    

DOI:10.1002/mrm.1910390124

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1998

数据来源: WILEY

ISSN:0740-3194    

DOI:10.1002/mrm.1910390101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1998

数据来源: WILEY