Does Hypertension Affect the Recovery of Renal Functions after Reversal of Unilateral Ureteric Obstruction?

Research has demonstrated that hypertension can lead to an exaggeration in the renal functional and histological changes caused by ureteral obstruction. These changes were particularly observed shortly after the release of a relatively brief period of unilateral ureteral obstruction (UUO). However, the long-term impact of hypertension on the recovery of renal functions has not been investigated beyond the immediate period after UUO reversal. In order to investigate this effect, a group of spontaneously hypertensive rats (G-SHR, n = 11) and a group of normotensive Wistar Kyoto rats (G-NTR, n = 11) were subjected to a 48 h reversible left UUO. The impact of UUO was then examined 45 days after the reversal of obstruction. The glomerular filtration rate, renal blood flow, and the fractional excretion of sodium in the post-obstructed left kidney (POK) showed similarities to the non-obstructed right kidney (NOK) in both groups. However, the changes in the albumin creatinine ratio, renal injury markers, pro-apoptotic markers, and histological changes in the G-SHR were much more pronounced compared to the G-NTR. We conclude that hypertension continues to have a significant impact on various aspects of renal injury and function, even several weeks after UUO reversal.

The Effect of Hypertension on the Recovery of Renal Dysfunction following Reversal of Unilateral Ureteral Obstruction in the Rat.

Both ureteral obstruction (UO) and hypertension are common conditions that affect kidney functions. Hypertension and chronic kidney disease are closely associated with an overlapping and intermingled cause-and-effect relationship. The effect of hypertension on the renal dysfunction following reversible UO has not been studied previously. To study this effect, spontaneously hypertensive (G-HT, n = 10) and normotensive Wistar (G-NT, n = 10) rats underwent 48-h reversible left unilateral UO (UUO), and the effect of UUO was studied 96 h following UUO reversal. The glomerular filtration rate, renal blood flow, and renal tubular functions such as the fractional excretion of sodium in the post-obstructed left kidney (POK) in both groups were significantly altered compared with the non-obstructed right kidney (NOK). However, the alterations in the G-HT were significantly more exaggerated when compared with the G-NT. Similar findings were observed with the histological features, gene expression of kidney injury markers, pro-inflammatory, pro-fibrotic and pro-apoptotic cytokines, and pro-collagen, as well as tissue levels of apoptotic markers. We conclude that hypertension has significantly exaggerated the alterations in renal functions and other parameters of renal injury associated with UUO.

Despite initial recovery of GFR, long-term renal functions deteriorate following short periods of unilateral ureteral obstruction.

Following the release of short periods of unilateral ureteral obstruction (UUO), glomerular filtration rate (GFR) recovers by time. However, research in experimental animal models has demonstrated the presence of an ongoing element of renal interstitial fibrosis a few weeks following UUO reversal. Interstitial fibrosis can cause deterioration in GFR, and it is not known whether it leads to an ongoing slow deterioration in other renal functions despite the apparent initial recovery postreversal. To investigate this, rats underwent a 72-h reversible UUO. Renal functions of nonobstructed and previously obstructed kidneys were measured 1, 4, and 18 mo postreversal. GFR in nonobstructed and previously obstructed kidneys was similar up to 18 mo postreversal. However, there was ongoing tubulointerstitial fibrosis, and the degree of tubular atrophy and dilatation deteriorated by time. This was associated with an increase in urinary albumin leakage and alterations in renal injury markers, proinflammatory and profibrotic cytokines, and p53 from 4 mo onward despite the recovery in GFR. In conclusion, several aspects of renal functions continue to deteriorate following reversal of relatively short periods of UUO despite the initial recovery in GFR. This might stimulate further research in this area and might have clinical implications in terms of determining the best time for intervention following acute ureteral obstruction and long-term monitoring of these individuals.