S. Amer et Ja. Brown, GLOMERULAR ACTIONS OF ARGININE VASOTOCIN IN THE IN-SITU PERFUSED TROUT KIDNEY, American journal of physiology. Regulatory, integrative and comparative physiology, 38(4), 1995, pp. 775-780
Recent measurements of plasma arginine vasotocin (AVT) in teleost fish
suggest circulating concentrations of 10(-10)-10(-12) M. Previous stu
dies of the renal actions of AVT in vivo suggest both diuretic and ant
idiuretic effects, but at unknown circulating concentrations. We have
investigated the renal actions of 10(-9) and 10(-11) M AVT in vitro us
ing an in situ perfused kidney preparation of rainbow trout (Oncorhync
hus mykiss). AVT increased vascular resistance (56%), reduced perfusat
e flow (P < 0.001), and increased interrenal aortic pressure (P < 0.00
1). AVT resulted in dose-dependent decreases in urine flow rates, glom
erular filtration rates, and tubular transport maxima for glucose. AVT
at 10(-11) M reduced relative free water clearances (P < 0.01), but u
rine/plasma inulin ratios were unchanged, whereas 10(-9) M AVT reduced
urine/plasma inulin ratios (P < 0.01) and increased relative free wat
er clearances (P < 0.05). The filtering population of glomeruli was re
duced by both 10(-11) and 10(-9) M AVT to approximately one-third of t
he glomeruli, and a similar population of arterially perfused but nonf
iltering glomeruli emerged. These results demonstrate that physiologic
al concentrations of AVT have potent glomerular antidiuretic action in
the trout, reducing the number of functional glomeruli, and imply red
uced individual nephron filtration rates.