The renal hemodynamic effects of Aspirin in newborn and young adult rabbits

A group of neonatal (n=10) and 12-week-old (n=12) anesthetized, ventilated New Zealand white rabbits received an acute i.v. dose (40 mg/kg body weight ) of acetylsalicylic acid (ASA, Aspirin). In the neonatal animals, i.v. ASA caused within 20 min a significant (P<0.01) fall in renal blood flow and g lomerular filtration rate (GFR), with an equally significant (P<0.01) incre ase in filtration fraction and renal vascular resistance. The latter indica tes greatly augmented renal vasoconstriction or more precisely reduction in intrarenal vasodilatation by inhibition of vasodilatory prostaglandin (PG) synthesis. Urine volume decreased. The 12-week-old young adult animals res ponded in a similar, but significantly attenuated fashion. These experiment s demonstrate that inhibition of PG synthesis in neonatal animals causes ve ry rapid, reversible vasoconstriction, with a reduction in GFR. In addition , this study confirms previous observations that the renal hemodynamic resp onse to the inhibition of PG synthesis is far more pronounced in neonatal a nimals than in (young) adult rabbits.