Effect of the inhibitor of angiotensin I converting enzyme on endocrine function and renal perfusion in haemorrhagic shock.

The present study was undertaken to investigate the effect of inhibition of angiotensin I converting enzyme on endocrine responses and renal perfusion in haemorrhagic shock. Plasma levels of vasopressin (VP), aldosterone, and plasma renin activity (PRA), and renal cortical tissue blood flow were measured both in control dogs and in those treated with an inhibitor of angiotensin I converting enzyme (SQ20881). The drug was administered with an intention of preventing vasoconstriction induced by angiotensin II and to improve tissue perfusion. No significant differences were found in plasma levels of vasopressin, aldosterone and plasma renin activity between control and SQ20881-treated groups. Secondary elevation of blood pressure following haemorrhage was significantly delayed and reduced by the administration of the inhibitor. Decrease in renal cortical tissue blood flow was observed in the SQ20881-treated group. It is suggested that angiotension II appears to play a role in spontaneous recovery of arterial blood pressure following haemorrhage. Furthermore, angiotensin II does not seem to play an important role in the stimulation of secretion of vasopressin in response to haemorrhage. Our data failed to demonstrate any favourable effects of inhibition of angiotension I converting enzyme on renal perfusion during haemorrhagic shock in dogs.