Sporidesmin concentrations in the bile of sheep resistant or
susceptible to sporidesmin dosing
R.J. Fairclough, B.L. Smith
Ruakura Animal Research Station, Ministry of Agriculture and
Fisheries, Hamilton
Proceedings of the New Zealand Society of Animal Production.
1983, 43: 213-216
Twelve ram lambs bred for resistance or susceptibility to
sporidesmin dosing were operated on under general anaesthetic and T-way
catheters inserted into the common bile duct to facilitate collection of
bile. After a recovery period of 14 days the animals were given an oral
dose of sporidesmin at a rate of 0.08 mg/kg/d over 3 consecutive days.
A trace amount of 35S-labelled sporidesmin was also given on the first
and third day of dosing to allow quantitation of sporidesmin appearing
in the bile fluid. Bile samples were collected at 0.5 to 1 hourly
intervals for 24 hours after the first and third dosing. Results showed
bile concentrations of sporidesmin increasing to a maximum in 1 to 3
hours and then declining over the following 20 hours. There was
considerable individual variation among animals in the pattern of uptake
and in the maximal concentration reached after dosing. In some animals
there was a marked increase in biliary sporidesmin from the first to the
third oral dosing while other animals showed little observed increase at
these times. A positive correlation (P<0.05) was found between liver-
damage score at slaughter and maximum sporidesmin concentration in bile
after the third but not the first oral dosing. These findings raise the
possibility that an initial or 'potentiating' dose of sporidesmin may be
required before 'susceptibility' or ' resistance' to facial eczema is
expressed.
Keywords: NZSAPAB;
Sporidesmin; sheep; bile; facial eczema; pharmacokinetics
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Last Updated 03-05-1997
