Cardiovascular effects of arginine vasotocin, atrial natriuretic peptide, and epinephrine in freshwater eels
Oudit, G.Y.; Butler, D.G.
American Journal of Physiology 268(5 Pt 2): R1273-R1280
1995
ISSN/ISBN: 0002-9513 PMID: 7771590 Document Number: 443784
The effects of 150 ng/kg iv injections of arginine vasotocin (AVT), eel atrial natriuretic peptide (ANP), and epinephrine (Epi) on the cardiovascular dynamics of resting freshwater eels, Anguilla rostrata were studied. Injection of AVT into the caudal vein significantly increased cardiac output (CO) from 15.3 to 23.6 ml cntdot min-1 cntdot kg-1 primarily by increasing stroke volume. Mean dorsal aortic pressure (PDA) also increased. Estimated branchial shunting (2.54 ml cntdot min-1 cntdot kg-1) was elevated by 130% because of an increased proportion of CO, indicating a vasoconstriction of the branchial arterioarterial pathway. In contrast, Epi reduced the fraction of CO perfusing the arteriovenous pathway. Epi also produced a positive chronotropic effect, increased CO and systemic vasoconstriction, resulting in a vasopressor response. These changes occurred earlier than those of AVT and ANP. Pressor responses triggered by AVT and Epi preceded the increases in CO. Injections of 150 and 200 ng/kg ANP caused a reduction in P-DA due to a decrease in CO (and SV) but failed to modulate systemic resistance. The change in CO was the primary contributor to the pressor (and depressor) responses elicited by the three hormones.