Development of an in situ perfused kidney preparation for elasmobranch fish: action of arginine vasotocin

Abstract

Development of an in situ perfused kidney preparation for elasmobranch fish: action of arginine vasotocin. Am J Physiol Regulatory Integrative Comp Physiol 282: R1636-R1642, 2002 10.1152/ajpregu.00810.2000.-Acclimation of the European lesser-spotted dogfish Scyliorhinus canicula to reduced environmental salinity [85-70% seawater (SW)] induced a significant diuresis in addition to a significant decrease in plasma osmolality in vivo. The threshold for this diuresis was determined to be 85% SW. Therefore, S. canicula acclimated to 85% SW was selected for further study as a diuretic model in the development of an in situ perfused kidney preparation. The renal role of arginine vasotocin (AVT) in the in situ perfused trunk preparation was investigated. In SW, perfusion of 10 Ϫ9 and 10 Ϫ10 M AVT resulted in a glomerular antidiuresis and decreases in tubular transport maxima for glucose and perfusate flow. In 85% SW, 10 Ϫ10 M AVT had no significant effect on these renal parameters with the exception of transport maxima for glucose and perfusate flow. Tubular parameters remained unchanged by either 10 Ϫ9 or 10 Ϫ10 M AVT. The results demonstrate that the perfused kidney preparation was a viable tool for the investigation of renal parameters in elasmobranch fish and that AVT induced a glomerular antidiuresis.antidiuresis; seawater; Scyliorhinus canicula; dogfish; neurohypophysial hormones MARINE ELASMOBRANCHS MAINTAIN their plasma isoosmotic or slightly hyperosmotic to that of the surrounding environment, primarily due to the retention of urea (22). Plasma sodium and chloride concentrations are generally higher than those found in marine teleosts, but the fish still face a continuous influx of NaCl across semipermeable membranes, particularly the gills (18,20). Due to the plasma iso/hyperosmolality, some influx of water will occur and urea will be lost to the environment across permeable surfaces, along a concentration gradient. Elasmobranchs are not capable of producing a hyperosmotic urine with respect to body fluids, and the kidneys are not the major site of NaCl excretion (17). It appears that renal retention of urea may be a more important function for the kidney in elasmobranch fish (7).Arginine vasotocin (AVT), a homologue of arginine vasopressin (AVP) in mammals, is the major neurohypophysial peptide in lower vertebrates. It has been characterized in all elasmobranchs examined to date (1, 2). In addition to AVT, the European lesserspotted dogfish Scyliorhinus canicula also has the oxytocinlike peptides, phasvatocin and asvatocin, which occur in roughly equal molar amounts in the pituitary (13). AVT is also present in the pituitary in a proportional amount that is lower by about a factor of 20 (13). This low pituitary level was thought to reflect a permanent secretion of AVT (2). Although accurate levels of AVT have been measured in teleosts, the presence of additional neurohypophysial peptides in elasmobranchs and the potential for these to cross-react with the antiserum have meant that it has not been possible at...

Glomerular Effects of AVT on the In Situ Perfused Trunk Preparation of the Dogfish

“…We have previously reported that perfusion with 10 −9 M AVT caused a significant decrease in urine flow rate (48% reduction) and glomerular filtration rate (GFR) (52% reduction) 2. The present data demonstrate that this glomerular antidiuresis following perfusion with 10 −9 M AVT was associated with a significant reduction in the proportion of filtering glomeruli and significant increases in the proportion of perfused but not filtering and non‐perfused glomeruli (Fig.…”

Effect of low environmental salinity on plasma composition and renal function of the Atlantic stingray, a euryhaline elasmobranch

“…Interestingly, adjusted for GFR, osmolal clearance (C osm / GFR) was 5-fold less, and free water clearance (C H 2 O /GFR) 20-fold higher, for Atlantic stingrays maintained in harbor water than that obtained for European lesser-spotted dogfish (Scyliorhinus canicula) acclimatized to 85% seawater stepwise over 6 days (56). These findings indicate that although stenohaline dogfish can be acclimatized to an estuarine salinity, their ability to reabsorb solute independently of water (and thus generate free water) is markedly less than that of the euryhaline stingray at a similar salinity.…”

Measurement of blood volume in the elasmobranch fish Scyliorhinus canicula following acute and long‐term salinity transfers

“…Upon initiation of transfer to 100% SW, these animals were in a hyposmotic state and therefore osmotically lost water across the semi‐permeable surfaces. Long‐term acclimation to reduced salinity has also been shown to significantly increase basal urine flow rate in S. canicula (Wells et al , 2002). Under these circumstances, animals in the current study will have continued to lose water, even after urine flow rates had returned to levels equivalent to those of long‐term acclimated 100% SW animals, while plasma osmolality remained hyposmotic to the environment.…”