Circulation in trout gills: the relationship between branchial perfusion and the width of the lamellar blood space

Abstract

Experiments were carried out to examine the role of pillar cell contraction in changes in branchial flow rate in isolated-perfused gill arches and in the distribution of blood flow in the gills in vivo. Although administration of adrenaline caused a 43% increase and acetylcholine caused a 59% decrease in the efferent branchial flow rate through isolated gill arches, the average width of the lamellar blood space was actually larger in the gills of the acetylcholine-treated group. In the in vivo experiments, only about 60% of the secondary lamellae were actively perfused at a given instant. The average width of the lamellar blood space was the same whether or not the lamellae were being perfused. It was concluded that pillar cell contraction was not involved in the observed differences in branchial circulation between the experimental groups in vitro or in vivo.