Logan A G, Morris R, Rankin J C
J Exp Biol. 1980 Oct;88:239-47. doi: 10.1242/jeb.88.1.239.
Micropuncture techniques have been used to investigate kidney function in lampreys adapted to hyperosmotic media. Plasma electrolyte concentrations were maintained well below corresponding concentrations in the external environment. Urine composition was variable, but generally showed high concentrations of magnesium, sulphate and chloride ions. Lampreys in 50% sea water produced urine which was hypo or iso-osmotic to plasma, whereas those in 100% sea water produced hyperosmotic urine. Urine flow rate in 50% sea water was one tenth of that in fresh water, due to a reduction in filtration rate and an increase in water reabsorption by the kidney. As in fresh water, little if any filtered water was reabsorbed by the proximal segment. Almost 90% of filtered water was reabsorbed by the kidney of 100% sea water lampreys and most of this must have occurred in the distal and collecting segments.
微穿刺技术已被用于研究适应高渗介质的七鳃鳗的肾功能。血浆电解质浓度维持在远低于外部环境中相应浓度的水平。尿液成分各不相同，但通常显示出高浓度的镁、硫酸根和氯离子。处于50%海水环境中的七鳃鳗产生的尿液相对于血浆是低渗或等渗的，而处于100%海水环境中的七鳃鳗则产生高渗尿液。处于50%海水环境中的七鳃鳗的尿流率是淡水环境中的十分之一，这是由于滤过率降低以及肾脏对水的重吸收增加所致。与在淡水中一样，近端小管几乎不重吸收滤过水（如果有重吸收的话也极少）。几乎90%的滤过水被处于100%海水环境中的七鳃鳗的肾脏重吸收，其中大部分肯定发生在远端小管和集合小管。
