QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Summary Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Lapner, K. N. Articles by Perry, S. F. Search for Related Content PubMed PubMed Citation Articles by Lapner, K. N. Articles by Perry, S. F.

The role of angiotensin II in regulating catecholamine secretion during hypoxia in rainbow trout Oncorhynchus mykiss

Katherine N. Lapner and Steve F. Perry^*

Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, Ontario, Canada K1N 6N5

View larger version (11K): [in a new window]   Fig. 1. The effects of acute hypoxia (40 mmHg=5.3 kPa; at the vertical dashed line) on plasma levels of adrenaline (filled columns) and noradrenaline (open columns) in rainbow trout (Oncorhynchus mykiss) previously infused (0.2 ml min–1) with (A) saline (N=9) or (B) nicotine (1.3x10–5 mol kg–1 h–1; N=17) for 60 min under conditions of normoxia. Plasma catecholamine levels were measured at ‘Pre’, 10 min and 60 min of infusion and during acute hypoxia. Values are shown as means + S.E.M. An asterisk denotes a statistically significant increase (P<0.05) from the corresponding ‘Pre’ value or ‘60 min’ pre-hypoxia value. A dagger indicates a statistically significant difference (P<0.05) from the control (saline-infused) value.

View larger version (12K): [in a new window]   Fig. 2. The effects of acute hypoxia (40 mmHg=5.3 kPa; at the vertical dashed line) on plasma levels of adrenaline (filled columns) and noradrenaline (open columns) in rainbow trout (Oncorhynchus mykiss) previously infused (0.2 ml min–1) with nicotine (1.3x10–5 mol kg–1 h–1) for 60 min under conditions of normoxia. An injection of (A) atropine (1 µmol kg–1; N=9), (B) methysergide (10–8 mol kg–1; N=9) or (C) lisinopril (10–4 mol kg–1; N=20) was administered after 40 min of nicotine infusion. Plasma catecholamine levels were measured at ‘Pre’, 10 min and 60 min of infusion and during acute hypoxia. Values are shown as means + S.E.M. An asterisk denotes a statistically significant increase (P<0.05) from the corresponding ‘Pre’ value or ‘60 min’ pre-hypoxia value. A dagger indicates a statistically significant difference (P<0.05) from the control value (saline injection; Fig. 1B).

View larger version (15K): [in a new window]   Fig. 3. Plasma levels of adrenaline (filled columns) and noradrenaline (open columns) during acute hypoxia (40 mmHg=5.3 kPa) in rainbow trout (Oncorhynchus mykiss) previously infused (0.2 ml min–1) with nicotine (1.3x10–5 mol kg–1 h–1) for 60 min under conditions of normoxia. To block specific receptors or enzymes, injections were administered at 40 min (20 min prior to hypoxia) using saline (control; N=17), atropine (muscarinic receptor antagonist; 1 µmol kg–1; N=9), methysergide (serotonin receptor antagonist; 10–8 mol kg–1; N=9) or lisinopril (angiotensin-converting enzyme inhibitor; 10–4 mol kg–1; N=20). Values are shown as means + S.E.M. A dagger indicates a statistically significant difference (P<0.05) from the control value.

View larger version (11K): [in a new window]   Fig. 4. The effects of acute hypoxia (40 mmHg=5.3 kPa) on plasma angiotensin II levels in rainbow trout (Oncorhynchus mykiss) previously infused (0.2 ml min–1) with nicotine (1.3x10–5 mol kg–1 h–1) or saline (data were combined as there were no significant differences in [angiotensin II] between the two groups) for 60 min under conditions of normoxia. An injection of saline (filled columns; N=15) or lisinopril (10–4 mol kg–1; open columns; N=15) was made prior to hypoxia at 40 min infusion. ‘Pre’ samples were taken immediately prior to the onset of hypoxia. Values are shown as means + S.E.M. An asterisk denotes a statistically significant increase (P<0.05) from the corresponding ‘Pre’ value. A dagger indicates a statistically significant difference (P<0.05) from the control value.

View larger version (10K): [in a new window]   Fig. 5. The effects of acute hypoxia (40 mmHg=5.3 kPa; at the vertical dashed line) on plasma levels of adrenaline (filled columns) and noradrenaline (open columns) in rainbow trout (Oncorhynchus mykiss) previously infused (0.2 ml min–1) with saline for 60 min under conditions of normoxia. An injection of (A) saline (control; N=9) or (B) lisinopril (10–4 mol kg–1; N=10) was made prior to hypoxia at 40 min saline infusion. Plasma catecholamine levels were measured at ‘Pre’, 10 min and 60 min of infusion and during acute hypoxia. Values are shown as means + S.E.M. An asterisk denotes a statistically significant increase (P<0.05) from the corresponding ‘60 min’ pre-hypoxia value. A dagger indicates a statistically significant difference (P<0.05) from the control value.