AJP - Regulatory, Integrative and Comparative Physiology, Vol 262, Issue 5 933-R937, Copyright © 1992 by American Physiological Society
Micropuncture study of avian kidney: effect of prolactin
J. R. Roberts and W. H. Dantzler
Department of Physiology, University of New England, Armidale, New South Wales, Australia.
Renal function was studied in anesthetized European starlings (Sturnis
vulgaris) by micropuncture and clearance techniques. A previous study had
shown some changes in the renal function of birds in molt. Endogenous
prolactin levels have been shown to be elevated at this time. In the
present study, renal function was studied during the infusion of an
isotonic sodium chloride solution and then when ovine prolactin was added
to the infusion. Ovine prolactin resulted in an elevation of plasma urate
concentration but had no significant effects on other plasma parameters or
on the concentration of the various ions in tubular fluid samples. Urine
flow rate was significantly higher during prolactin infusion, although
whole animal glomerular filtration rate, single nephron glomerular
filtration rate, and the percentage fluid reabsorption in the proximal
tubule (up to the point of micropuncture) were unaltered. The whole animal
fractional excretions of sodium and chloride were significantly higher,
those of magnesium and potassium were significantly lower, and the
fractional excretion of phosphate tended to be lower during prolactin
infusion. At the level of the proximal tubules of the reptilian-type
nephrons, prolactin infusion caused a slight reduction in the net
reabsorption of sodium and chloride. Therefore the main effects of
prolactin on renal function are occurring in the distal nephron of the
reptilian-type nephrons or in the mammalian-type nephrons. It appears that
prolactin may affect renal function in avian species and that these actions
may be modulated by a range of factors as has been demonstrated in mammals.
