UNILATERAL RENAL PAPILLECTOMY VIA LASER OR INCISIONAL TECHNIQUES - CHRONIC FUNCTIONAL-EFFECTS IN THE DOG

Objective. To determine if selective renal papillectomy would impair u rinary concentrating ability, thereby decreasing urinary calcium conce ntration. Methods. Left papillectomy was performed in dogs using eithe r incisional (n = 6) or Neodymium:yttrium-aluminum-garnet (Nd:YAG) las er (n = 5) techniques. Split renal function studies were then performe d four months postoperatively to determine the effect on multiple para meters including inulin and para-aminohippurate (PAH) clearance, free water reabsorption, and calcium concentrations. Partially infarcted ki dneys (n = 6) were evaluated in a similar fashion to determine the rol e of impaired glomerular filtration rate (GFR) in the observed concent rating defect occurring after papillectomy. Results. Papillectomized k idneys demonstrated impaired free water reabsorption, resulting in a d ecreased urinary osmolality and an increased fractional excretion of w ater. Osmolar clearance [Na+] and Na+ excretion were unaffected by pap illectomy, whereas [Ca++] was significantly reduced. While a slight de fect in free water reabsorption existed following partial infarction, urinary osmolality was only minimally decreased, fractional excretion of water was unchanged, and Na+ excretion was decreased. Conclusions. The concentrating defect induced by papillectomy via either sharp exci sion or laser ablation is due to loss of medullary tissue and is great er than the defect resulting from impaired GFR, which is presumably du e to decreased medullary solute delivery and increased flow of water i n remaining nephrons. Since the physiologic consequences of papillecto my (formation of less concentrated urine with decreased [Ca++]) have p otential clinical applicability, further study of this concept is warr anted.