Cardiorespiratory upregulation during seawater acclimation in rainbow trout: effects on gastrointestinal perfusion and postprandial responses

Abstract

Brijs J, Gräns A, Ekström A, Olsson C, Axelsson M, Sandblom E. Cardiorespiratory upregulation during seawater acclimation in rainbow trout: effects on gastrointestinal perfusion and postprandial responses.

Exposure to seawater increases intestinal motility in euryhaline rainbow trout (Oncorhynchus mykiss)

“…Interestingly, the residence time approximately matches the temporal responses of intestinal motility documented in the present study (∼2 days), as well as essential cardiovascular modifications associated with osmoregulation in trout (e.g. gastrointestinal blood flow and cardiac output increase between ∼2 and 4 days) (Brijs et al, 2015(Brijs et al, , 2016(Brijs et al, , 2017b. Collectively, this may indicate that, even in the face of increased predation pressure and mortality associated with these shallow estuarine habitats (Aldvén et al, 2015;Gregory, 1993), certain physiological modifications in migrating salmonids that are likely triggered by exposure to waters of increasing salinity must occur prior to completing the migration to sea.…”

“…Following this period, one group of fish remained in FW, whereas another group were netted and transferred to similar 1000 l tanks containing artificial SW (salinity 30-33 ppt; source of artificial sea salt: Grotech, GmbH, Ahorn, Germany; pH 7.6-8.0; conductivity 45-65 mS cm −1 ; [ions] Na + 425-530, K + 4-7, Ca 2+ 6-8 mmol l −1 ) at 10-11°C. In accordance with the SW acclimation protocol used in our previous study (Brijs et al, 2016), the animals were acclimated to these conditions for at least 6 weeks prior to experimentation. During this time there was no mortality and all fish were voluntarily feeding on dry commercial trout pellets (9 mm Protec Trout pellets, Skretting, Stavanger, Norway) three times per week.…”

Effects of coeliacomesenteric blood flow reduction on intestinal barrier function in rainbow trout Oncorhynchus mykiss

“…For a detailed description of the surgical technique used see Brijs et al . (). Individual fish ( n = 3, mean ± S.E.…”

In vivo aerobic metabolism of the rainbow trout gut and the effects of an acute temperature increase and stress event

“…The coeliacomesenteric artery branches from the dorsal aorta proximate to the efferent branchial vessels and divides progressively to supply the stomach, intestine, gallbladder, liver and gonads (Seth et al, 2011). The blood flow probe was placed around the coeliacomesenteric artery as described in detail by Brijs et al (2016). Once the flow probe was in position, the lead was exited via the incision and secured to the skin with 3.0 braided silk sutures.…”

“…Thus, considering the relatively high gut blood flow, and assuming that gut tissues have a similar oxygen extraction to other tissues, gut ṀO 2 should constitute a substantial proportion of whole-animal ṀO 2 in fish. Furthermore, gut blood flow increases by ∼70-150% following a meal (Axelsson et al, 1989(Axelsson et al, , 2000Eliason et al, 2008;Gräns et al, 2009a;Seth et al, 2008;Thorarensen and Farrell, 2006), by ∼100% when acclimating to seawater (Brijs et al, 2015(Brijs et al, , 2016 and by ∼50-150% when acutely warmed (Gräns et al, 2009b(Gräns et al, , 2013. If these substantial increases in gut blood flow coincide with similar increases in gut ṀO 2 , then the metabolic demands of the gut have the potential to limit the aerobic capacity for other activities such as locomotion (i.e.…”