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Publication Detail

Title: Lead induction of crop dysfunction in pigeons through a direct action on neural or smooth muscle components of crop tissue.

Authors: Boyer, I J; Cory-Slechta, D A; DiStefano, V

Published In J Pharmacol Exp Ther, (1985 Sep)

Abstract: Lead acetate solutions administered p.o. to pigeons produce crop stasis. Crop dysfunction may be an indirect effect on crop activity by a direct interaction with the cerebellum or some other site associated with lead-induced ataxia. Alternatively, crop stasis may be due to the direct interaction of lead with sites on the smooth muscle or neural elements in crop tissue. A behavioral test for ataxia was performed on pigeons given lead by crop intubation or i.m. injection. Blood lead concentrations were also monitored. Lead-induced ataxia was separable from lead-induced crop dysfunction depending on the route of lead administration, suggesting that lead-induced crop stasis is not secondary to toxicity at a site associated with ataxia. Intramuscular treatment produced crop stasis more readily than did crop intubation. This probably reflects different mechanisms of absorption and metabolism. A Tris-succinate medium was devised which accommodated the solubility characteristics of lead, permitting studies of crop tissue in vitro. Lead chloride added to crop tissue in tris-succinate medium caused a concentration-related reversible relaxation. Crop circular muscle was more sensitive to Pb++ than was longitudinal muscle, in agreement with the effects of other agonists. The EC30 of crop circular smooth muscle in plasma was 1000 microM PbCl2 compared to 3 microM in Tris-succinate medium. The results suggest that lead induces crop dysfunction by acting either directly on crop smooth muscle or on neural elements in crop tissue.

PubMed ID: 2993587 Exiting the NIEHS site

MeSH Terms: Animals; Ataxia/chemically induced; Cerebellum/drug effects; Columbidae; Crop, Avian/drug effects*; Crop, Avian/innervation; Culture Media; Dose-Response Relationship, Drug; Electric Stimulation; Inclusion Bodies/drug effects; Lead/blood; Lead/toxicity*; Male; Muscle Contraction/drug effects; Muscle, Smooth/drug effects*

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