It is well accepted that postischemic reperfusion promotes functional and morphological impairment which may be related to
oxygen free-radical-mediated membrane damage. A new purified bioactive compound,
calcitonin-gene-related peptide (CGRP), is known to be not only a potent
vasodilator but also a cytoprotective agent. This study was designed to observe whether CGRP has a protective effect on the ischemic kidney. Male Sprague-Dawley rats were subjected to a 45-min period of renal
ischemia followed by 60 min of reperfusion. At the beginning of the reperfusion, 12 rats were given intravenous saline and served as controls whereas 5 rats were given CGRP, 10 micrograms/kg intravenously. After reperfusion the kidneys were removed for light- and electronmicroscopy, and the lipid peroxidation product
malonaldehyde (MDA) was assayed by
thiobarbituric acid (TBA) colorimetry. The results demonstrated that the serum
creatinine (Scr) and renal MDA content in the CGRP group were significantly lower than those in the control group. The mean values for Scr were 0.75 +/- 0.09 vs 0.93 +/- 0.05 mg/dL or 62.8 +/- 9.7 vs 82.2 +/- 4.4 mumol/L (p less than 0.05), respectively; while the mean values for MDA were 18.71 +/- 2.13 vs 30.32 +/- 1.78 nmol/100 mg (ww) (p greater than 0.05), respectively. The same signals of
free radicals in the ischemic-reperfused kidney with or without CGRP were found by electron spin resonance. Morphological studies demonstrated that the treatment with CGRP ameliorated the ischemic-
reperfusion injury to both renal brush borders and mitochondria. The results showed that CGRP has a protective action on
ischemia-reperfusion renal injury by decreasing lipid peroxidation of membranes and suggest that it may be a beneficial agent for
therapy of
acute renal failure.