Branchial blood flow distribution in the blue shark (Prionace glauca) and the leopard shark (Triakis semifasciata).
Electromagnetic flow (EMF) quantification of total cardiac stroke flow is not feasible for most elasmobranchs because the vascular anatomy precludes probe placement adjacent to the heart and proximal to all afferent branchial arteries (aba). Most previous studies report a fractional cardiac flow, made with the EMF probe placed on the ventral aorta between the innominate arteries and aba 3. Estimation of total cardiac stroke flow from such data requires a flow correction factor obtained by sacrificing the fish, and carrying out a two step in situ/in vitro flow calibration procedure which is based on tenuous assumptions. Ventral aortic blood flow measurements using the EMF techniques were carried out on large blue sharks, and radiographic imaging studies of ventral aortic and branchial blood flow were done on leopard sharks to verify previously estimated fractional cardiac stroke flow correction factors. The innominate flow fraction determined for both species in these studies are similar and agree with previous estimates for elasmobranchs. EMF data for Prionace show 38% of cardiac stroke flow goes to the innominate arteries, 23% into aba 3, 12% into aba 4, and 27% into aba 5. Radiographic analyses with Triakis reveal that 32% of its cardiac stroke volume flows into the innominate arteries which is in agreement with the in situ/in vitro fractional flow estimate (33%).
Lai
N C
NC
Physiological Research Laboratory, University of California, San Diego, La Jolla 92092.
Graham
J B
JB
Bhargava
V
V
Lowell
W R
WR
Shabetai
R
R
D000818:Animals; D001011:Aorta / Q000502:physiology; D001916:Brachial Artery / Q000000981:diagnostic imaging / Q000502:physiology*; D005880:Gills / Q000098:blood supply / Q000000981:diagnostic imaging / Q000502:physiology*; D011859:Radiography; D012039:Regional Blood Flow; D012754:Sharks / Q000502:physiology*