Japanese Journal of Veterinary Research;Volume 42, Number 3-4

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THE INHIBITORY ACTION OF LEAD ON MECHANICAL RESPONSES OF THE PROVENTRICULAR SMOOTH MUSCLE IN THE CHICK

KUBOTA, Kazufumi;ITO, Shigeo;OHTA, Toshio;NAKAZATO, Yoshikazu;OHGA, Akira

Permalink : http://hdl.handle.net/2115/2472
JaLCDOI : 10.14943/jjvr.42.3-4.109
KEYWORDS : Autonomic transmission;Ca^<2+> influx;chick stomach

Abstract

The purpose of the present experiments was to examine the mechanism of the proventricular dilatation caused by lead in the isolated vagus nerveproventricular smooth muscle preparation of the chick. Lead caused dose- and time-dependent inhibition of contractions induced by vagal stimulation, transmural stimulation and externally applied acetylcholine (ACh). Vagally evoked contraction was much more sensitive to the inhibitory action of lead than the contractile response to ACh. The lower the frequency of transmural stimulation, or the lower the concentration of ACh was applied, the greater the inhibitory action of lead on the evoked smooth muscle contraction. The results suggest that proventricular impaction occurring in lead poisoning results from the pre- and postsynaptic inhibition of the vagus nerve-smooth muscle transmission.

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