On plasma volume measurement and the effect of experimental stress in the themale tilapia, Oreochromis mossambicus, maintained in fresh water

Abstract

Plasma volumes in male tilapia (Oreochromis mossambicus) of different size were estimated following intracardial injection of radioiodinated human serum albumin ((125)I-HSA), coupled with short-term, early sampling transient response analysis of 1251-HSA disappearance from the plasma pool. This approach circumvents vascular marker leakage problems associated with constant steady state indicator dilution methods, minimizes some sampling and mixing problems, and simplifies analysis of the data. Changes in hematological parameters due to experimental stress were also studied, because the fish were not chronically cannulated. Results were used in a novel way to correct estimates of plasma volume upward by 15%, thereby providing a potentially useful alternative approach to vascular volume measurement in species where stress-eliminating or reducing techniques, e.g., cannulation, are impractical or infeasible. Hematrocrits increased 38% at the onset, from 24.9% to 34.4%, and remained essentially constant during the 60 minute kinetic study, and plasma osmolalities increased 7%. Corrected plasma volumes Vp (ml) were a linear function of body weight (BW). The group mean Vp was 2.93% of BW and corresponding blood volumes were 3.9% of BW.

Cohesive social behaviour shortens the stress response: the effects of conspecifics on the stress response in lake sturgeon Acipenser fulvescens

“…The transient increases in plasma osmolality and ionic concentrations (Cl − , and ), as well as the trends seen for other ions (Na + and Br − ) are contrary to normal changes in freshwater fishes, where catecholamine‐induced changes in gill permeability and branchial circulation, in order to increase gas transfer and oxygen uptake, cause decreased osmolality and ion concentrations (Wendelaar Bonga, 1997). Because the transient increase is observed in osmolality, as well as in most of the ions, it may be due to either decreased plasma volume from water moving out of the circulation and into tissues (Okimoto et al , 1994), or haemoconcentration caused by increased urine flow rates (Wood & Randall, 1973; Tervonen et al , 2006). In Acipenser , most of the studies that have measured osmotic and ionic changes were evaluated in the context of salinity changes (Allen & Cech, 2007).…”

Is the primitive regulation of pituitary prolactin (tPRL177 and tPRL188) secretion and gene expression in the euryhaline tilapia (Oreochromis mossambicus) hypothalamic or environmental?

“…This is indicated by the increase in serum osmolality (but not circulating PRLs) in the control fish of study II (see Results). One possible mechanism for such an increase in serum osmolality in the FW-adapted sham-operated group of study II is an acute stress-related decrease in plasma volume following handling or confinement (see Okimoto et al 1994, Wendelaar Bonga 1997.…”

Corticotropin-releasing hormone in the teleost stress response: rapid appearance of the peptide in plasma of tilapia (Oreochromis mossambicus)

“…However, we exclude the pituitary as a source of plasma CRH as no time-dependent changes were found in pituitary CRH content during capture. In the case that plasma CRH originated from the neural part of the pituitary gland, a detectable reduction of about 170 pg of pituitary CRH content would have occurred (3% of the body weight is plasma in tilapia (Okimoto et al 1994)). …”