Characterization of G proteins in obstructed kidneys

Role of leukocyte adhesion molecules in monocyte/ macrophage infiltration in weanling rats with unilateral ureteral obstruction

BACKGROUND

Unilateral ureteral obstruction (UUO) of rats is a well-established model for studying obstructive nephropathy. Meanwhile, pathophysiology of pediatric obstructive nephropathy is not well understood. In this report, we studied monocyte/macrophage infiltration and expression of intercellular adhesion molecule 1 (ICAM-1) and macrophage antigen 1 (Mac-1) in weanling rats with UUO.

METHODS

Three-week-old male Sprague-Dawley rats underwent left unilateral ureteral ligation. Both obstructed kidneys (OBK) and contralateral kidneys (CLK) were harvested at 3, 6, 12, 24, 72 and 120 h after surgery. Monocyte/macrophage infiltration and expression of ICAM-1 and Mac-1 were evaluated immunohistochemically, and results were compared with those of sham-operated control rats (SOK).

RESULTS

Monocyte/macrophage infiltration was observed in the interstitium and perivascular region in the cortex of OBK within 6 h. The CLK and SOK showed slight monocyte/macrophage infiltration. Expression of ICAM-1 was markedly observed in the periarterial and peritubular interstitium and in renal cortical peritubular capillaries 12 h after obstruction. In CLK and SOK, ICAM-1 was slightly expressed in the endothelium of microvessels and parietal linings of Bowman's capsule. Expression of Mac-1 was detected mainly in cells infiltrating the perivascular interstitium in OBK. In CLK and SOK, few Mac-1-positive cells were observed.

CONCLUSIONS

Adhesion molecules, ICAM-1 and Mac-1, are expected to recruit monocyte/macrophage infiltration into OBK of weanling rats with UUO.

Role of protein kinase C in cisplatin nephrotoxicity

BACKGROUND

Cisplatin is widely used in cancer treatment. The major disadvantage of this antitumor agent is its nephrotoxicity. The mechanism of cisplatin-induced nephrotoxicity has not been clarified. Recent evidence suggests protein kinase C (PKC)-related signal transduction pathways may modulate cisplatin-induced cytotoxicity.

METHODS

The effect of cisplatin administration on PKC expression in the kidney and the effect of a PKC inhibitor on cisplatin-induced renal impairment were investigated in rats.

RESULTS

A single intraperitoneal injection of 8 mg/kg cisplatin induced remarkable damage in the proximal tubules located in the outer medulla, which was associated with impaired renal function, within 48 h. An immunoblotting study revealed marked expression of alpha-PKC in membrane fractions of medullary tubules prepared from cisplatin-treated rats. In addition, pretreatment with the PKC inhibitor (H-7) protected kidneys from cisplatin-induced damage.

CONCLUSIONS

These findings suggest that the nephrotoxic effects of cisplatin may, in part, be related to PKC activation in the renal tubules.