Renal Function in the European Eel (Anguilla Anguilla L.): Changes in Blood Pressure and Renal Function of the Freshwater Eel Transferred to Sea-Water

Abstract

A method for the study of renal function and measurement of mean ventral and dorsal aortic blood pressure for the freshwater and seawater\x=req-\ adapted eel, and during transfer of the animal from fresh water to sea-water, is described.Freshwater eels have higher resting blood pressure, p-aminohippuric acid (PAH) and inulin clearance rates and urine flow than seawater eels. Urine from freshwater animals has low Na, K, Ca, Mg and Cl concentrations, while the clearance rate of inorganic phosphate exceeded that of inulin. Urine from seawater animals has high Na, Ca, Mg and Cl concentrations while that of inorganic phosphate was low. Clearance rates for Ca and Mg greatly exceeded those of inulin.During transfer from fresh water to sea-water there was an initial fluctuation in blood pressure, urine flow and PAH and inulin clearance rates which lasted about 2 hr. Thereafter these gradually declined to values observed for the seawater-adapted animal.The significance of PAH and inulin clearance rates in the study of renal function in the eel and in teleosts in general is discussed.

Renal Diuresis After Injections of the Freshwater Eel and Antidiuresis Arginine Vasotocin in (Anguilla Anguilla L.)

“…The basic characteristics of kidney function in freshwater eels used in this investi¬ gation largely confirm and also extend previous studies made in this and other laboratories (Sharratt, Chester Jones & Bellamy, 1964;Chester Jones, Henderson & Butler, 1965;Butler, 1966;Oide & Utida, 1968;Chester Jones, Chan & Rankin, 19696). As in all freshwater teleosts there is a brisk production of urine which results from a 60% fractional excretion of the filtered fluid load, and in addition there are low fractional solute excretion rates (Hickman & Trump, 1969;Lahlou, 1970).…”

Elastic-like tissue, a new component of the renal glomerular capillary wall in a cartilaginous fish

“…In fact, the absence of elastic fibers in the marine rays of this present study would then corroborate the speculation of Mundel et al (1988) concerning the functional significance of the microfibrils. However, the presence of both tubular microfibrils and amorphous material in the glomerular wall of the freshwater rays would seem to contradict these arguments, except that the glomerular filtration rate of these river rays is higher than their marine counterparts, as is the case for bony fish (Lahlou 1967;Chester-Jones et al 1969). The general consensus that elasmobranchs evolved in marine environments, and secondarily invaded freshwater (Brooks et al 1981 ;Griffith 1987), strongly suggests a functional role for the microfibrils and amorphous material, since they cannot be viewed as an "evolutionary appendage" from a marine ancestor.…”

Measurement of Plasma Cortisol Levels in the Eel Anguilla Anguilla in Relation to Osmotic Adjustments

“…The high rate of renal water flow in FW may be stimulated by cortisol in A. anguilla (Chan, Rankin & Chester Jones, 1969) and by prolactin, though not by ACTH, in Fundulus kansae (Stanley & Fleming, 1967). The adaptive decrease in urine flow after transfer of A. anguilla to SW (Chester Jones, Chan & Rankin, 19696) must, according to our results, take place against a background of the same or higher plasma cortisol as in FW, and therefore is perhaps likely to be a consequence of reduced secretion of prolactin in SW. Ad¬ ditionally, there is the possibility that renal adaptation to SW could be due to changes in endocrine glands other than the adenohypophysis and adrenal cortex (Chan et al 1969). …”