The effects of softwater acclimation on respiratory gas transfer in the rainbow trout Oncorhynchus mykiss
نویسندگان
چکیده
Gill O2 uptake, CO2 excretion, ventilation and blood respiratory/acid­base variables were evaluated in control and softwater-acclimated trout (Oncorhynchus mykiss) to test the hypothesis that gill chloride cell (CC) proliferation, elicited by 2 weeks of softwater exposure, impairs the diffusion of respiratory gases across the gill. The proliferation of CCs in softwater fish was verified using light microscopy, and its impact on respiratory gas transfer was assessed in vivo by continuous monitoring of arterial blood PO2 (PaO2), PCO2 (PaCO2) and pH (pHa) using an extracorporeal blood circulation under conditions of normoxia and graded hypoxia [water PO2 (PwO2) was lowered from 20.0 kPa to 5.3 kPa within 20 min]. During normoxia, ventilation frequency was significantly higher in the softwater trout (78±4 versus 57±4 breaths min-1; mean ± s.e.m.), while ventilation amplitude was similar in both groups (1.0­1.1 cm opercular displacement). PaCO2 and plasma HCO3- concentration were significantly lower in the softwater fish and the blood acid­base status was characterized by a mixed respiratory alkalosis and metabolic acidosis such that blood pH was not statistically different between the two groups. CO2 excretion (2.5­2.8 mmol kg-1 h-1) and O2 uptake rates (2.3­5.1 mmol kg-1 h-1), as measured during normoxia, were unaffected by acclimation to soft water. During hypoxia, ventilation frequency and amplitude increased in the control trout, whereas only ventilation amplitude increased in the softwater-acclimated fish. The rate of PaO2 reduction during hypoxia was significantly greater in the softwater fish (0.84±0.06 versus 0.65±0.06 kPa PaO2 kPa-1 PwO2) and, at the most severe level of hypoxia (PwO2=5.3 kPa), PaO2 was significantly lower in the softwater fish. The rate of PaCO2 reduction (caused by hyperventilation) was significantly lower in the softwater-acclimated fish (0.002±0.001 versus 0.005±0.001 kPa PaCO2 kPa-1 PwO2; mean ± s.e.m.; P<0.06) and, indeed, was not statistically different from zero. Blood pH did not change significantly during hypoxia in either group but, through much of the hypoxic period (7­15 kPa PwO2), pHa was statistically lower in the softwater-acclimated fish. These results demonstrate that exposure of trout to soft water for 2 weeks is associated with proliferation of lamellar CCs and impaired branchial gas transfer. Hyperventilation was identified as a compensatory physiological adjustment.
منابع مشابه
The effects of the acetic acid “pain” test on feeding, swimming, and respiratory responses of rainbow trout (Oncorhynchus mykiss): A critique on Newby and Stevens (2008)
(2008). The effects of the acetic acid " pain " test on feeding, swimming, and respiratory responses of rainbow trout (Oncorhynchus mykiss).
متن کاملThe comparative effects of dietary supplementation with Pediococcus acidilactici and Enterococcus faecium on feed utilization, various health-related characteristics and yersiniosis in rainbow trout (Oncorhynchus mykiss Walbaum, 1792)
This study examined the effects of feeding of two dietary probiotics on growth performance and feed utilization, intestinal colonization and related health criteria, biochemical parameters, hematological indices, and immune parameters and protection against Yersinia ruckeri in Oncorhynchus mykiss during a period of 56 days. The study included 3 groups:1(a control group of fish, 2) a group of fi...
متن کاملEnhancement of immune responses of rainbow trout (Oncorhynchus mykiss) fed a diet supplemented with Aloe vera extract
The effects dietary supplementation with Aloe vera extract (AE) on the immunity responses and hematological parameters of rainbow trout (Oncorhynchus mykiss) fry were evaluated in eight weeks trial. 600 rainbow trout (O. mykiss) fry with an average initial body weight of 13±0.05g were randomly allocated into two treatment groups including placebo-treated group (control) and A. vera extract-trea...
متن کاملCold tolerance performance of westslope cutthroat trout (Oncorhynchus clarkii lewisi) and rainbow trout (Oncorhynchus mykiss) and its potential role in influencing interspecific hybridization
Hybridization between rainbow trout (Oncorhynchus mykiss (Walbaum, 1792)) and westslope cutthroat trout (Oncorhynchus clarkii lewisi (Girard, 1856)) occurs commonly when rainbow trout are introduced into the range of westslope cutthroat trout. Typically, hybridization ismost common inwarmer, lower elevation habitats, butmuch less common in colder, higher elevation habitats. We assessed the tole...
متن کاملEffect of Gamma irradiation and frozen storage on microbial quality of Rainbow trout (Oncorhynchus mykiss) fillet
The effect of gamma radiation (1, 3 and 5 kGy) on microbial quality of farmed rainbow trout (Oncorhynchus mykiss) fillets which were stored under frozen conditions (-20° C) was studied by measuring microbiological changes in 5 months. Gamma irradiation and increasing of frozen storage time had significant effects (P < /i>
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- The Journal of experimental biology
دوره 198 Pt 12 شماره
صفحات -
تاریخ انتشار 1995