Analysis of the effects of topical renal hypothermia on lung tissue after kidney ischemia and reperfusion in rats.
OBJECTIVE
To evaluate whether topical renal hypothermia (TRH) at different levels of temperature has protective effects on lung tissue after renal I/R, through an analysis of organ histology and inflammatory markers in lung tissue.


METHODS
Twenty-eight male Wistar rats were randomly allocated across four groups and subjected to renal ischemia at different levels of topical renal temperature: normothermia (no cooling, 37°C), mild hypothermia (26°C), moderate hypothermia (15°C), and deep hypothermia (4°C). To induce I/R, the vessels supplying the left kidney of each animal were clamped for 40 minutes, followed by reperfusion. After four hours, another procedure was performed to harvest the tissues of interest. TNF-α, IL-1β and myeloperoxidase activity were measured in lung tissue. Histological analysis was performed in hematoxylin and eosin-stained lung specimens.


RESULTS
Induction of renal I/R under deep topical hypothermia resulted in a significant decrease in lung concentrations of TNF-α compared with normothermic I/R (p<0.05). A trend toward significant correlation was found between lung IL-1β concentration and intensity of hypothermia (Spearman r=-0.37; p=0.055). No difference was found in myeloperoxidase activity or histologic injury between groups.


CONCLUSIONS
Topical renal hypothermia reduces activation of the inflammatory cascade in the lung parenchyma. However, tissue-protective effects were not observed.
Department of Surgery, Universidade Federal do Rio Grande do Sul, Rio Grande do Sul, Brazil.
Marlon Roberto
MR
Fiorentini
Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil.
Emanuel Burck dos
EB
Santos
Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil.
Larisse
L
Longo
Department of Pathology, School of Medicine, Universidade Federal do Rio Grande do Sul, Rio Grande do Sul, Brazil.
Lúcia Maria
LM
Kliemann
Department of Surgery, School of Medicine, Universidade Federal do Rio Grande do Sul, Rio Grande do Sul, Brazil.
Walter José
WJ
Koff
Department of Surgery, School of Medicine, Universidade Federal do Rio Grande do Sul, Rio Grande do Sul, Brazil.
Carlos Otávio
CO
Corso
D000818:Animals; D003080:Cold Temperature; D004797:Enzyme-Linked Immunosorbent Assay; D007036:Hypothermia, Induced / Q000379:methods*; D053583:Interleukin-1beta / Q000378:metabolism*; D007668:Kidney / Q000098:blood supply* / Q000473:pathology; D008168:Lung / Q000098:blood supply* / Q000473:pathology; D008297:Male; D009195:Peroxidase / Q000378:metabolism*; D011897:Random Allocation; D017208:Rats, Wistar; D015427:Reperfusion Injury / Q000209:etiology / Q000378:metabolism*; D015203:Reproducibility of Results; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
D053583:Interleukin-1beta; D014409:Tumor Necrosis Factor-alpha; D009195:Peroxidase