CORTICOMEDULLARY PROCOLLAGEN ALPHA-1(IV) MESSENGER-RNA LEVELS AND LOCALIZATION AFTER SUBTOTAL NEPHRECTOMY

The relationships between tubular hypertrophy/hyperplasia, procollagen alpha 1(IV) mRNA levels, and the development of tubular basement memb rane thickening were studied in male Sprague-Dawley rats subjected to subtotal renal ablation and sacrificed 2 or 15 days later, Tubular hyp ertrophy and hyperplasia were demonstrable at 2 days, however no incre ment in procollagen alpha 1(IV) mRNA levels was discerned at that time , demonstrating a dissociation between mRNA levels for classical type IV collagen and tubular enlargement, At 15 days, tubular procollagen a lpha 1(IV) mRNA levels did increase approximately 2-fold (p < 0.002), localizing predominantly in proximal tubules in the deep cortex and ou ter medullar?, stripe, At this time point, there was still no signific ant correlation to tubular enlargement, but there was a significant co rrelation to tubular basement membrane thickening (r = 0.89, p < 0.01) , These studies demonstrated that an increase in mRNA for classical ty pe IV collagen is not required for the development of hypertrophy, and that the increment is a better marker for matrix expansion than it is for hypertrophy.