Effects of feeding and temperature on gastrointestinal blood flow in the Antarctic fish Pagothenia borchgrevinki; different or just another teleost?

2008 ◽  
Vol 150 (3) ◽  
pp. S117
Author(s):  
M. Axelsson
Keyword(s):  
Blood Flow ◽  
Antarctic Fish ◽  
Pagothenia Borchgrevinki ◽  
Gastrointestinal Blood Flow ◽  
The Antarctic

A role of 5-HT2 receptors in the gill vasculature of the antarctic fish Pagothenia borchgrevinki.

1998 ◽  
Vol 201 (14) ◽  
pp. 2129-2138 ◽  
Author(s):  
L Sundin ◽  
W Davison ◽  
M Forster ◽  
M Axelsson
Keyword(s):  
Receptor Antagonist ◽  
Vascular Resistance ◽  
Receptor Agonist ◽  
Antarctic Fish ◽  
Cardiovascular Responses ◽  
Arterial Oxygen ◽  
Nerve Fibres ◽  
Aortic Blood ◽  
Pagothenia Borchgrevinki ◽  
The Antarctic

This study was conducted to describe the cardiovascular responses to intra-arterial injections of serotonin in the Antarctic fish Pagothenia borchgrevinki and to elucidate the underlying mechanisms. Immunohistochemistry was used to localise serotonin-containing cells within the gills. 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 in combination with Doppler flow measurement. An extracorporeal loop with an in-line oxygen electrode allowed continuous measurements of arterial oxygen pressure PaO2. Pre-branchial injection of serotonin (5-hydroxytryptamine, 5-HT) or the 5-HT2 receptor agonist alpha-methylserotonin increased the branchial vascular resistance and ventral aortic pressure, while the 5-HT1 receptor agonist piperazine was without effect. The branchial vasoconstriction produced by serotonin injection was completely blocked by the 5-HT1/5-HT2 receptor antagonist methysergide and the branchial vasoconstriction produced by WIDTH="9" HEIGHT="12" ALIGN="BOTTOM" NATURALSIZEFLAG= alpha-methylserotonin injection was completely blocked by the specific 5-HT2 receptor antagonist LY53857. The results suggest that the 5-HT2 receptor alone mediates the branchial vasoconstriction. Serotonin also mediated a methysergide-sensitive reduction in PaO2, the reduction being greatest when the pre-injection PaO2 value was high. 5-HT-immunoreactive cells and nerve fibres were present within the gill tissues. All the 5-HT-immunoreactive cells were located on the efferent side of the filaments, but 5-HT-immunoreactive nerve fibres were found lining both of the branchial arteries. Our findings demonstrate a potential serotonergic control system for the gills in Pagothenia borchgrevinki. In contrast to its effects on the branchial vasculature, serotonin produced a methysergide-insensitive decrease in the systemic vascular resistance. However, neither the specific 5-HT1 nor 5-HT2 receptor agonists produced a decrease in the resistance of the systemic vasculature. The nature of the serotonergic receptor(s) inducing vasodilation in teleost fish is uncertain.

Nervous control of the spleen in the red-blooded Antarctic fish, Pagothenia borchgrevinki

1996 ◽  
Vol 270 (3) ◽  
pp. R599-R604 ◽  
Author(s):  
S. Nilsson ◽  
M. E. Forster ◽  
W. Davison ◽  
M. Axelsson
Keyword(s):  
Antarctic Fish ◽  
Cholinergic Innervation ◽  
Maximal Contraction ◽  
Nervous Control ◽  
Major Function ◽  
Pagothenia Borchgrevinki ◽  
The Antarctic ◽  
Stimulation Of

The mechanisms of splenic control in the Antarctic fish, Pagothenia borchgrevinki, were investigated using isolated spleen and mesenteric artery strips in vitro and perfused spleen preparations in situ. Splenosomatic index (SSI) [100 x (spleen wt/body wt)] and hematocrit were determined in animals treated with atropine and phentolamine. Atropine injection increased the SSI from 0.60 +/- 0.06 to 0.89 +/- 0.04, whereas phentolamine decreased SSI to 0.45 +/- 0.03. In atropine-injected fish, hematocrit was 18.6 +/- 1.4 before and 6.6 +/- 0.8% 3 h after injection. Electrical stimulation of the splenic nerves produced biphasic flow responses. In 11 of 12 tested preparations, atropine (3 x 10(-7) to 10(-6) M) abolished the response, suggesting a major cholinergic component in the splenic innervation. Isolated spleen strip preparations contracted in response to carbachol, a response that was antagonized by atropine. The response to acetylcholine was markedly enhanced by the specific cholinesterase inhibitor BW-284c51. Catecholamine effects were somewhat irregular, and maximal contraction force with epinephrine and norepinephrine was 41 and 56%, respectively, of the carbachol response. The results suggest a mainly, if not solely, cholinergic autonomic control of the borch spleen, and a major function of the cholinergic innervation in the control of hematocrit in this species.

scholarly journals Hypoxic Responses in a Fish From a Stable Environment: Blood Oxygen Transport in the Antarctic Fish Pagothenia Borchgrevinki

1989 ◽  
Vol 141 (1) ◽  
pp. 97-111 ◽  
Author(s):  
R. M.G. WELLS ◽  
G. C. GRIGG ◽  
L. A. BEARD ◽  
G. SUMMERS
Keyword(s):  
Haemoglobin Concentration ◽  
Oxygen Affinity ◽  
Antarctic Fish ◽  
Hypoxic Exposure ◽  
Blood Oxygen ◽  
Low Oxygen ◽  
Pagothenia Borchgrevinki ◽  
Oxygen Carrying Capacity ◽  
O2 Delivery ◽  
The Antarctic

The effects of hypoxic exposure on whole-blood oxygen-affinity were examined in the antarctic fish Pagothenia borchgrevinki. Fish exposed to POO2 = 60 mmHg for 11–14 days at −1.5°C had a P50 value of 20.6±4.8mmHg (S.D., N=13) at pH8.16, compared with 31.1 ±4.3mmHg (N=10) at pH8.00 for normoxic fish. Exposure to low oxygen levels resulted in a significant (66 %) rise in haemoglobin concentration, and erythrocyte [ATP] decreased by approximately 27%. There was no evidence for erythrocyte swelling. An aberrant gill morphology was observed in six fish and these showed unexpectedly high erythrocyte ATP levels. Oxygen-carrying capacity increased by approximately 40% in hypoxic fish and was correlated with a 34 % decrease in spleen mass. Despite the fact that antarctic fish have exceptionally low demands for oxygen and are unlikely ever to encounterenvironmental hypoxia, this antarctic fish has the necessary machinery to respondto hypoxia in a way that is typical of teleosts that naturally inhabit oxylabile environments. The ability to make short-term adaptive changes in the O2 delivery system in response to hypoxic exposure may be typical for vertebrates in general, rather than a feature seen only in those organisms which encounter environmental hypoxia on a regular basis.

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