Hemodynamic and renal responses were studied under acute hemodilution alone and combined with sodium nitroprusside controlled hypotension. Fifteen mongrel dogs were divided into 2 groups : a hemodilution alone (HD) group and a hemodilution combined with hypotension (HP) group. Hemodilution was performed by withdrawing 20ml/kg blood and replacing it with 6 % Hydroxyethyl starch in saline (Salin-HES^®, MW : 70, 000) at 1.5-fold the volume of blood. Hypotension was produced during 90 minutes by intravenous infusion of sodium nitroprusside at the mean arterial pressure of 70 mmHg, group HP only. The results were as follows:
1) CI increased significantly after hemodilution in both groups. However, CI increased significantly compared with control value during hypotensive period in group HP.
2) PaO₂ and PaCO₂ did not change all experimental period in comparison with those of control value in both groups.
3) Renal blood flow increased significantly compared with control value in two groups after hemodilution, and renal blood flow did not differ significantly in all experimental periods between the two groups.
4) Renal tissue oxygen tension was not significant between before and after hemodilution, and renal tissue oxygen tension did not differ significantly in all experimental periods between the two groups.
The findings in the present study suggested that when combined with hemodilution, sodium nitroprusside is a preferable hypotensive agent, in regarding to the renal variables.