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Comparative investigation of the pharmacology of fish and mammalian neuromuscular systems

Thesis/Dissertation ·
OSTI ID:7023975

Neuromuscular pharmacology has been extensively studied in mammals but there have been few investigations examining the neuromuscular systems of fish. In situ experiments have shown that the basic cholinergic characteristics of fish neuromuscular junctions are different from those of mammals. In order to further understand the nature of these differences, the nicotinic acetylcholine receptors (AChR) of rat and buffalo sculpin (Enophrys bison) neuromuscular junctions and the AChR of electric ray (Torpedo california) electroplax, were investigated using receptor binding analysis. A rapid filtration assay was utilized to measure (/sup 125/I)..cap alpha..-BGT binding to tissue membranes. Scatchard analysis of (/sup 175/I)..cap alpha..-BGT binding was performed on sculpin pectoral muscle rat gastrocnemius, rat denervated gastrocnemius, and Torpedo electroplax. The affinity constant was similar for all tissues studied. In competition studies, d-tubocurarine had the highest affinity for the (/sup 125/I)-..cap alpha..-BGT binding site in all tissues, illustrating the nicotinic nature of the binding sites. Acetylcholine had high affinity for the rat gastrocnemius binding site and low affinity for the sculpin pectoral muscle and Torpedo electroplax binding site. Atropine had high affinity for the sculpin pectoral muscle binding site when compared to the rate gastrocnemius and Torpedo electroplax binding site, indicating that the sculpin pectoral site may have some mixed muscarinic-nicitinic characteristics. These results indicate that there are definite qualitative as well as quantitative differences between the fish skeletal muscle nicotinic receptor and the nicotinic receptor of fish electroplax and rat skeletal muscle.

Research Organization:
Oregon State Univ., Corvallis (USA)
OSTI ID:
7023975
Country of Publication:
United States
Language:
English