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VOLUME LOADI.'G EFfEC13ON THE HEARt USING "P NMR 147
This inditates Nat 2 .3-DPG is present in too small a qudntity to cause a problem with
contamination of in vira hean spectm. There were twro blood peaks (peak 1 . peak 2)
in the s'P NMR spectra of cat blood . Peak one had a chemical shift consistent with
dtat of P, . Peak two had a chemical shift consistent with that of a phosphodiester .
Thus.any increase in the P, peak ofin viraspectm would most likeiy be that generated
fmnt intracellular metabolism .
Pln:ciologira/ lmrnrntirnr
~ After control spectra were acquired . volume o.Yrload (high output state) was produced
by opening the previously constructed abdominal aorta-vena cava shunts . a'P
spectra were obtained sequentially at 6-min intervals o .er I to 2 h or acute volume
loading. Upon opening of the AVS . all cats had the typical increase in pulse pressure
which is a good indication that the shunt has been opened .
N.71R Data Anahsis
Each free induction decay (FlD) was Fourier tmnsformed and filtered with 10 Hz
line bmadening Spectra .verc phased and curve fi0ed(Lorcnt8an) using a least-squarex
fit algorithm. Areas under each peak were integrated . Each spcctrvm contained the
following peaks from left to right : inorganic phosphate . phosphocrcatine. and adenosine
triphosphate (ATP: T . a . tT). Figs. 3 and 4. Ratios of P,/PCr and PCr/ATP were used
to estimate the slatc ofoaidati•r phosphopiation . The chemical shift of P, with respect
to PCr was used to determine the pH of myocardial cells during physiological intervention
.
To determine the reproducibility of"P NhfR data, the following was done . Under
• contrd conditions (no physiological intervention) . five sets of spectra were obtained
at the beginning of each esperfinent and at the end of each experiment for each cat .
P,IPCr and PCr/ATP data were averaged and the standard deviation was determined .
TTere was ±6% variability for P,/PCr ratios from acquisition of one slxctnnn m the
next and t 108% variability for PCr/ATP ratios. Thus, there is mme random variability
in "P NMR data which must be acknowledged when responses to physiological in•
tervention areevalualed . A change in the P~/PCr mtio of greater than 61, and a ch ange
in the PCr/ATP ratio of greater than i0't, must ocrur for a responsc to be considered
due to physiological intervention and not due to random variability .
Bioenergetir data as determined by P,/PCr and PCr/ATP ratios were corrclated
with mechanical function as determined by hean m1e x systolic blood pressureprodun
lHR x SBP is an estimate of oxygcn consumption (27)) with a linear regression algorithm
. In addition, in order to follow changes in the above-mentioned parameters
• with time and intervention (i .e . . to observe the effects of continuous modulation of
feedback control ofchanges in wark load on metabolism and vice versa). percentage
changes of P,/PCr, PCr/ATP. and HR x SBP from control were plotted with respect
• to time and intervention .
•
http://legacy.library.ucsf.edu/tid/fpe59c00/pdf
RESULTS
Although all animals were prepared and treated in a similar manner concerning
maintenance of stable physiological conditions (maintenance of arterial blood gases .
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