Blood pressure control in the antarctic fish Pagothenia borchgrevinki

• Main Authors: Michael Axelsson, Bill Davison, Malcolm Forster
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1994
• Subjects: Antarctic; The Antarctic; Antarc*
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.499.2198; http://jeb.biologists.org/content/190/1/265.full.pdf

The mechanisms of cardiovascular control in the Antarctic fish Pagothenia borchgrevinki were investigated during rest and swimming exercise using pharmacological tools to reveal the nature of the control systems involved. Simultaneous and continuous recordings of ventral and dorsal aortic blood pressure, heart rate and ventral aortic blood flow (cardiac output) were made using standard cannulation procedures and a single-crystal Doppler flowmeter. Exercise produced a clear and consistent decrease in dorsal aortic blood pressure caused by a decrease in systemic vascular resistance. At the same time, ventral aortic blood pressure increased owing to the combined effects of a markedly increased cardiac output (by about 80 %) and branchial vasoconstriction. Judged from the effects of the a-adrenoceptor antagonist prazosin, control of the branchial vasculature involves an a-adrenoceptor-mediated vasoconstriction, in addition to more traditional cholinergic vasoconstrictor and b-adrenoceptor-mediated dilatory mechanisms. The range of heart rates is large, from 3–4 beats min21 in individual fish during hypertensive bradycardia to about 28 beats min21 after atropine treatment. Both