Page 107 - The Toxicology of Fishes

Toxicokinetics in Fishes 87

Proximal Segment I – , Isosmotic? Proximal Segment II Isosmotic? Collecting Tubule

Marine Teleost GFR: 0.5 mL/kg hr (450 mOsm/kg H 2O) Na + , CI – , H 2O Isosmotic? Mg ++ , SO 4 H 2O Na + ,CI – , H 2O UFR = 0.3 mL/kg hr (410 mOsm/kg H 2O)

Blood Pressure Blood Flow AVI Angiotensin Prolactin Na + H 2O CI – Isosmotic Renal structure, proposed handling of water and NaCl, and effects of hormones in freshwater and marine teleosts. Solid and open arrows indicate active and passive movements, respectively. GFR, glomerular filtration rate; UFR, urine flow rate. Broken straight and U-shaped arrows indicate low permeability

Proximal Segment I Proximal Segment II Distal Tubule Collecting Tubule to water and possible Na and Cl cotransport, respectively. (Adapted from Nishimura, H. and Imai, M., Fed. Proc., 41, 2355–2360, 1982.)

Freshwater Teleost GFR: 4 mL/kg hr (280 mOsm/kg H 2O) ? Na + ,CI – ? H 2O Isosmotic? Na + ,CI – H 2O Isosmotic? H 2O Na + H 2O CI – CI – UFR = 3.0 mL/kg hr (20 mOsm/kg H 2O)

Blood Pressure Blood Flow AVI Angiotensin Cortisol ? Prolactin Na + H 2O FIGURE 3.15