The Effect of Epinephrine and Acetylcholine On the Distribution of Red Cells Within the Gills of the Channel Catfish (Ictalurus Punctatus)

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Abstract
The second pair of gill arches were perfused with 61Cr tagged red cells at constant pressure or constant flow and in the presence of 10−5 M epinephrine or 10−6 M acetylcholine. The tissues were quick frozen, lyophilized and the lamellae and alamellar filaments from the distal, mid and basal thirds of the filaments counted for radioactivity. At constant flow, epinephrine increased red cell space (RCS) in lamellae from basal and mid regions and decreased RCS in peripheral lamellae. The RCS in all alamellar filaments decreased. With constant pressure perfusion, epinephrine increased RCS in all lamellae while alamellar filamental RCS remained unchanged. Acetylcholine, at constant flow perfusion, decreased distal lamellar RCS and increased basal lamellar RCS. RCS decreased in distal and mid alamellar filaments during the same period. These data support the theory of lamellar recruitment as a means of increasing respiratory exchange and stress the importance of concomitant central cardiovascular changes in eliciting maximal response.