Plasma renin activity (PRA) was determined in conscious piglets between 1
and 50 days of age before and after treatment with saralasin and indornethacin. Following
drug treatment, animals were volume expanded with isotonic saline. Saralasin increased PRA
in piglets 1--5 and 18-22 days of age but not 45-50 days. Neither indome thacin nor VE
changed PRA at any age, Volume expansion of saralasin- and indomethacin-treated pigs
decreased PRA. Neonatal hyperrenincmia does not appear to result from renin release
stimulated by prostaglandins or by the absence of angiotensin II negative feedback. In
addition, the plasma half-Iife of renin was not different between young and more mature
animals suggesting that immature hepatic metabolism of renin cannot be entirely responsible
for the high PRA in newborns.
Fast atom bombardment (FAB) is useful for the characterization of all major metabolites of the analgesic acetaminophen (APAP). It is particularly useful for providing mass spectra of the polar glucuronide and sulfate conjugates which eluded identification by field desorption and other more conventional methods of ionization. A protocol is described for the use of FAB in the identification of urinary APAP metabolites isolated by reversed phase high-performance liquid chromatography (HPLC) following therapeutic dosages of the drug. A tentative set of recommendations for the off-line use of HPLC and FAB is directed towards solving problems encountered when using these two analytical techniques in concert. In addition, a method for calculating the signal to background ratio (S/B) for analyte peaks in FAB spectra from selected relative ion intensities is proposed. Examples are presented that show the potential of S/B as an empirical parameter for judging the quality of FAB spectra.
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