AJP - Renal Physiology, Vol 268, Issue 5 839-F846, Copyright © 1995 by American Physiological Society
Disturbances in renal microcirculation induced by myoglobin and hemorrhagic hypotension in anesthetized rat
F. Vetterlein, F. Hoffmann, J. Pedina, M. Neckel and G. Schmidt
Zentrum Pharmakologie und Toxikologie, Universitat Gottingen, Germany.
The question was studied of whether myoglobin (Mb), when released into the
general circulation during hemorrhagic hypotension (HH), causes
disturbances of renal blood flow. In anesthetized rats 250 mg/kg Mb was
intravenously infused within 1 h; HH at 50 mmHg with subsequent
retransfusion was induced for 30 min. By allowing two dyes to circulate for
1 and 3 min, respectively, and detecting their localization histologically
after rapid freezing of the organ, intrarenal distribution of capillary
blood flow was studied. In contrast to the results obtained with Mb or HH
alone, when Mb was infused during HH, the development of large areas within
cortex and medulla lacking any capillary perfusion was observed. In >
70% of the tissue, a distance > 60 microns to the next dye-labeled
capillary was found (in controls 0%). At this time total renal flow had
decreased from 5.3 to 0.20 ml/min (HH without Mb: 5.1 to 1.1 ml/min). It is
concluded that the observed changes in renal blood flow contribute to the
known direct nephrotoxic potential of Mb.
