AJP - Regulatory, Integrative and Comparative Physiology, Vol 246, Issue 2 211-R220, Copyright © 1984 by American Physiological Society
Hemodynamics and potentials in isolated flounder gills: effects of catecholamines
R. M. Stagg and T. J. Shuttleworth
Branchial hemodynamics and transepithelial potentials were investigated in
an isolated perfused gill preparation from the flounder (Platichthys flesus
L.). An analysis of the pressure-flow profiles suggests that the gill is
compliant but that the physical relationships of pressure and flow are
complex. Epinephrine has a bimodal effect with an initial vasoconstriction
followed by a vasodilation, the latter response being much smaller than
that usually seen in teleosts. Pharmacological analysis shows 1) an
alpha-mediated vasoconstriction of the arterial and venous pathway,
associated with a redistribution of flow away from the venous pathway, and
2) a small beta-mediated vasodilation of the arterial pathway only. An
electrical potential (inside positive) was measured across the isolated
gill, bathed and perfused with an identical saline. This potential was
recorded, despite the venous system being open to the external bath, and
was independent of both arterial and venous flows. Epinephrine caused a
significant decline in this potential, which could be resolved into a large
inhibitory alpha-mediated response and a small beta-mediated stimulation.
