Abstract
Myography and an isolated, perfused gill arch preparation were used to investigate the actions of drugs on the gill vasculature of an Antarctic teleost fish, Pagothenia borchgrevinki. Serotonin produced a dose-dependent vasoconstriction of the afferant branchial arteries, the gill arch and the efferent branchial arteries, and was the most potent vasoconstrictor tested. Acetylcholine, at concentrations exceeding 1 × 10-6M, vasoconstricted the gill arch, but had a negligible effect on the branchial arteries. The responses to adrenaline, with and without the β-adrenergic blocking drug, sotalol and the effects of the β-adrenergic agonist drug isoprenaline indicated the presence of both α-adrenergic and β-adrenergic receptors in the gill vasculature, with the vasoconstrictory action of the former predominating in the efferent vasculature. Angiotensin II was without effect in either preparation. The results are a further demonstration of the dominance of vasoconstrictory responses in the control of gill cular resistance in P. borchgrevinki: which has been associated previously with the sub-zero temperatures at which the animals are found.
Published Version
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