Factors Affecting the Perfusion and Delivery of Curcuminoids and other Molecules to Teleost Muscle
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
The primary objectives of this thesis were: to explore potential delivery pathways of supportive molecules to teleost musculature, and combined with perfusion visualisation experiments, to generate a greater understanding of teleost white muscle perfusion. A Chinook salmon (Oncorhynchus tshawytscha) perfused isolated tail preparation was assessed as a delivery platform with limited results as perfusion to the white muscle did not replicate that in the live fish. A direct uptake delivery method, where hydrophobic molecules diffuse across the gill lamellae and accumulate in the blood and white muscle, was assessed with the aquatic anaesthetic isoeugenol (AQUI-STM). Snapper (Pagrus auratus) exposed to low (4.5±0.3 mg.L-1), medium (8.6±0.1 mg.L-1) and high (14.0±0.3 mg.L-1) isoeugenol concentrations had maximum plasma isoeugenol concentrations of 10.5, 5.8 and 4.9 times (low, medium and high) and white muscle concentrations 9.7, 4.6 and 1.9 times (respectively) the exposure concentration. Direct uptake delivery, compared with the perfused tail preparation, was a relatively non-invasive and non-technical method of delivery that has potential for large scale commercial application. The curcuminoids, which are strong antioxidants derived from the spice turmeric, were also shown to rapidly diffuse into the plasma and musculature of snapper. There were no short term benefits on white muscle metabolic rundown in fish treated with curcumnoids compared to a non-treated control. However, a short term accelerated storage trial suggested that snapper treated with curcuminoids showed reduced lipid peroxidation. The successful delivery of supportive molecules to the white muscle is dependent on perfusion. There is very little research on white muscle perfusion and how it is affected by changing environmental parameters. Cardiac performance and white muscle perfusion and haemoglobin saturation were recorded from anaesthetised snapper during acute progressive hypoxia and hypothermia (and recovery) in real time, using fibre optics. White muscle perfusion, as assessed by haemoglobin concentration, decreased during hypoxia and hypothermia. The intrinsic control of cardiac function and white muscle perfusion in an anaesthetised fish, and the adaptive significance of reduced white muscle perfusion during hypoxia and hypothermia are discussed.