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First published online January 5, 2005
Journal of Experimental Biology 208, 223-232 (2005)
Published by The Company of Biologists 2005
doi: 10.1242/jeb.01362

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Activation of the newly discovered cyclostome renin–angiotensin system in the river lamprey Lampetra fluviatilis

J. Anne Brown^1,*, Christopher S. Cobb^1,, Susan C. Frankling¹ and J. Cliff Rankin^2,

¹ School of Biological and Chemical Sciences, Hatherly Laboratories, University of Exeter, Prince of Wales Road, Exeter, EX4 4PS, UK
² Aquatic Biology Research Centre, Institute of Biology, University of Southern Denmark – Odense University, Hindsholmvej 11, DK-5300 Kerteminde, Denmark

View larger version (15K): [in a new window]   Fig. 1. Parallelism of the [Asn1,Val5]-Ang II radioimmunoassay standard curve (shown as means ± S.E.M., N=6) and serial dilution of an extract of pooled plasma from the river lamprey Lampetra fluviatilis. For details of the assay, see Materials and methods.

View larger version (25K): [in a new window]   Fig. 2. Blood volume depletion in river lampreys acclimated to Kerteminde seawater at 576 mOsm kg–1 (21 p.p.t.). The first blood sample (pre-volume depletion; open bars) was taken to achieve a 40% decrease in blood volume and a second sample (post-volume depletion; hatched bars) was collected after 30 min (N=10), 60 min (N=11) or 90 min (N=7). Data for (A) haematocrit (%), (B) plasma osmolality (mOsm kg–1) and (C) plasma angiotensin concentrations (pmol l–1) are shown (**P<0.01; ***P<0.001, paired t-tests).

View larger version (22K): [in a new window]   Fig. 3. (A) Haematocrit (%), (B) plasma osmolality (mOsm kg–1) and (C) plasma angiotensin concentrations (pmol l–1) of river lampreys acclimated to freshwater at 15 mOsm kg–1. Control lampreys (non-injected; black bars) were held under light anaesthesia for 15 min (N=8) and 30 min (N=4) in the absence of further manipulation. Experimental lampreys were blood sampled at either 15 min or 30 min after an i.p. injection of 1% body mass with either isosmotic saline (white bars; 120 mmol l–1 NaCl; 233 mOsm kg–1; N=5 at each time point) or hyperosmotic saline (cross-hatched bars; 4 mol l–1 NaCl; N=5 at 30 min; N=8 at 30 min). Different letters above error bars signify groups that differ significantly (ANOVA and post-hoc multiple comparison tests).

View larger version (12K): [in a new window]   Fig. 4. Effects of a rapid increase in environmental salinity (FW to 21 p.p.t.; 605 mOsm kg–1) on (A) plasma osmolality (mOsm kg–1), (B) blood haematocrit (%) and (C) plasma angiotensin concentration (pmol l–1) of river lampreys (N=8 at each time point: 0 h, 2 h, 4 h, 8 h and 24 h after transfer). Groups with different letters differ significantly (ANOVA and post-hoc multiple comparison tests). Asterisks signify groups that differ significantly from time 0 h(*P<0.05, **P<0.01, ANOVA followed by linear contrast analyses).

View larger version (12K): [in a new window]   Fig. 5. Effects of a rapid decrease in environmental salinity (from 26 p.p.t., 758 mOsm kg–1 to FW, 22 mOsm kg–1) on river lampreys. Blood samples were collected from a group of lampreys prior to transfer and further groups at 2 h, 4 h, 8 h and 24 h after transfer. Data for (A) plasma osmolality (mOsm kg–1; N=8 at each time point), (B) haematocrit (%; N=10 at 0h, 8 at all other time points) and (C) plasma angiotensin concentration (pmol l–1; N=9 at 0 h, N=8 at 2 h and 24 h, N=7 at 4 h and 8 h) are shown). Groups with different letters above error bars differed significantly (ANOVA and post-hoc multiple comparison tests).