The Effects of Recombinant IGF-I on Function and Nitric Oxide Synthase Activity of Kidney during Compensatory Hypertrophy

Cho, Chul Kyu; Han, Sang Won

Abstract

PURPOSE: Among renotropic agents, a growth hormone(GH) independent insulin-like growth factor I(IGF-I) improves renal function without inducing glomerulosclerosis and its potential for treating renal disease is increasing. To elucidate the effect of externally administered IGF-I toward enhancing renal function, the change in renal function and renal nitric oxide synthase(NOS) activity were investigated in the presence of the GH-IGF-I axis.
MATERIALS AND METHODS
100?150g Sprague-Dawley male rats were classified four groups according to experimental methods. The left kidney were removed in the rats of UNx group(uninephrectomy) and UNx+IGF-I group(IGF-I treated after uninephrectomy), and sham operation were done in the other rats of control group and Sham+IGF-I group(IGF-I treated after sham operation). The UNx+IGF-I group and Sham+IGF-I group were treated with 300microgram of recombinant IGF-I(rhIGF-I) daily for 5days after operation. The NOS activity were determined in the contralateral kidney tissues and the glomerular filtration rate(GFR) and effective renal plasma flow(ERPF) were determined in the serum.
RESULTS
The GFR, ERPF and NOS activity significantly increased compared to control after uninephrectomy(p<0.05). The GFR, ERPF and NOS activity were significantly different between UNx+IGF-I group and UNx group(p<0.05), but there was no significant difference between Sham+IGF-I group and Sham group after the administration of rhIGF-I.
CONCLUSIONS
Externally administered rhIGF-I increases GFR and ERPF via increasing NOS activity. We suggest that it is especially effective in improving the renal function of damaged kidneys.