Figure 1:

(A) Na⁺/K⁺-ATPase activity in the following tissues of long- and short-term freshwater (FW)-acclimated adult sea lampreys exposed to salinities (BW) of 17.5 and 25: G, gill; K, kidney; G1, anterior intestine; G2, middle intestine; and G3, posterior intestine. Short-term FW-acclimated sea lamprey freshwater control groups, FW control (n = 6, except gill and kidney n = 5 and middle intestine n = 8); brackish water 17.5 acclimated groups, BW-17.5 (n = 6, except anterior intestine n = 7); and brackish water 25, which are subdivided into osmoregulating and osmocompromised animals: BW-25 osmoregulating (n = 14, except kidney n = 13, anterior and posterior intestine n = 12 and n = 8, respectively); and BW-25 osmocompromised (n = 4, except posterior intestine n = 3). All long-term FW-acclimated sea lampreys tissue groups were n = 4. (B) Representative expression of NKA α1-subunit, Atp1a1 (1:1000). Values are relative to the respective freshwater control. Values are shown as means + SEM. Different upper case letters indicate significant differences between tissues irrespective of salinity. Different lower case letters denote significant differences with salinity within each tissue. Analysis was performed using a two-way ANOVA followed by a Holm–Sidak method test; P < 0.05.