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McLeay LM, Smith BL, Munday-Finch SC. Res Vet Sci. 1999
Apr;66(2):119-27.
Erratum in: Res Vet Sci 1999 Dec;67(3):313.
Tremorgenic mycotoxins paxilline, penitrem and lolitrem B,
the non-tremorgenic 31-epilolitrem B and electromyographic
activity of the reticulum and rumen of sheep.
Department of Biological Sciences, The University of Waikato,
Hamilton, PB 3105, New Zealand.
The mycotoxic tremorgens penitrem, paxilline and lolitrem B
had profound effects on electromyographic (EMG) activity of
smooth muscle of the reticulorumen in conscious sheep, with a
similar time course of action to their respective characteristic
effects on the induction (1 to 2, 15 to 20 and 20 to 30 minutes)
and the duration (1 to 2, 1 to 2 and 8 to 12 hours) of
tremoring. Responses to penitrem revealed a greater sensitivity
of smooth muscle than skeletal muscle. Effects included an
inhibition of the vagally-dependent cyclical A and B sequences
of contraction of the reticulorumen, an increase in their
amplitude and an excitation of local intrinsic activity
contributing to elevated baselines and the occurrence of chaotic
activity of the reticulum. The excitatory local effects were
partially blocked by atropine, indicating that stimulation of
muscarinic cholinoceptors was involved. Increased local activity
may mediate a reflex inhibition of cyclical contractions. A
non-tremorgenic isomer of lolitrem B (31-epilolitrem B) had no
effect on the reticulorumen. The intensity and duration of the
effects of lolitrem B, up to 12 hours, indicate that severe
disruption of digestion may occur in animals grazing
endophyte-infected pasture. Copyright 1999 W.B. Saunders Company
Ltd.
PMID: 10208889 |
